Form 424B3 DATA I/O CORP

Filed Pursuant to Rule 424(b)(3)
Registration No. 333-297902

PROSPECTUS

4,686,371 Shares of Common Stock

This prospectus relates to the resale, from time to time, by the selling stockholders identified in this prospectus under “Selling Stockholders,” of up to 4,686,371 shares of our common stock, no par value per share (“Common Stock”), which consists of 869,840 outstanding shares of Common Stock, 1,080,000 shares of Common Stock issuable upon exercise of outstanding warrants (the “Warrants”) and 2,736,531 shares of Common Stock issuable upon conversion of Series B Convertible Preferred Stock (the “Preferred Stock”). The securities were issued in connection with a private placement to the investors who participated in such offering.

We are not selling any securities under this prospectus, and we will not receive any proceeds from the sale of shares of our Common Stock by the selling stockholders under this prospectus. The selling stockholders will bear all brokerage commissions and similar expenses attributable to the sale of shares under this prospectus, and we will bear all costs, expenses and fees in connection with the registration of such shares. The selling stockholders may sell the shares of our Common Stock offered by this prospectus from time to time on terms to be determined at the time of sale through ordinary brokerage transactions or through any other means described in this prospectus. Such shares may be sold at fixed prices, at market prices prevailing at the time of sale, at prices related to prevailing market price or at negotiated prices. See “Plan of Distribution” beginning on page 11.

Our Common Stock is listed on the Nasdaq Capital Market under the symbol DAIO. On August 12, 2026, the reported sale price of our Common Stock on the Nasdaq Capital Market was $3.00 per share.

Investing in our securities involves certain risks. See the “Risk Factors” section beginning on page 5 of this prospectus, in any applicable prospectus supplement and in our Securities and Exchange Commission (“SEC”) filings that are incorporated by reference herein.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is August 12, 2026.

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

This prospectus relates to the resale, from time to time, by the selling stockholders identified in this prospectus under “Selling Stockholders” beginning on page 8, of up to 4,686,371 shares of our Common Stock held by the selling shareholders or issuable upon exercise or conversion of the Warrants and Preferred Stock. We are not selling any securities under this prospectus, and we will not receive any proceeds from the sale of shares of our Common Stock by the selling stockholders under this prospectus. To the extent the Warrants are exercised, we would receive the proceeds of the warrant exercise.

This prospectus is part of a registration statement on Form S-1 that we have filed with the SEC. This prospectus omits some of the information contained in the registration statement, and we refer you to the full registration statement for further information about us and the securities being offered by the selling stockholders under this prospectus. Before making an investment decision, you should read, in addition to this prospectus and the registration statement, any documents that we incorporate by reference in this prospectus, as referred to under “Incorporation By Reference” beginning on page 13, and the information under “Where You Can Find More Information” beginning on page 14. Any statement contained in the prospectus concerning the provisions of any document filed as an exhibit to the registration statement or otherwise filed with the SEC is not necessarily complete, and in each instance reference is made to the copy of the document filed. You should review the complete document to evaluate these statements. Further, you should not assume that the information in this prospectus or any documents incorporated by reference herein is accurate as of any date other than the date of each document. Our business, financial condition, results of operations or prospects may have changed since those dates.

Neither we nor the selling stockholders have authorized any other person to provide you with any information or to make any representations, other than those contained in this prospectus or incorporated by reference in this prospectus. If anyone provides you with additional, different or inconsistent information, you should not rely on it. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

The representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference into this prospectus were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreement, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

This prospectus and the documents incorporated by reference herein contain market data and industry statistics and forecasts that are based on independent industry publications and other publicly available information. Although we believe these sources are reliable, we do not guarantee the accuracy or completeness of this information, and we have not independently verified this information. In addition, the market and industry data and forecasts that may be included or incorporated by reference in this prospectus may involve estimates, assumptions and other risks and uncertainties and are subject to change based on various factors, including those discussed under the heading “Risk Factors” contained in this prospectus and under similar headings in other documents that are incorporated by reference herein. Accordingly, you should not place undue reliance on this information.

This prospectus may not be used to offer to sell, solicit an offer to buy or consummate a sale of securities unless it is accompanied by a prospectus supplement. If there is any inconsistency between information in this prospectus and any accompanying prospectus supplement, you should rely on the information in the latest supplement and documents incorporated by reference herein and therein.

This prospectus includes or incorporates by reference our trademarks and trade names, which are our property and are protected under applicable intellectual property laws. This prospectus also contains, or incorporates by

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reference trademarks and trade names that are the property of other organizations. Solely for convenience, trademarks and trade names referred to or incorporated by reference in this prospectus may appear without the ^® and ^™ symbols, but those references are not intended to indicate that we will not assert, to the fullest extent under applicable law, our rights, or that the applicable owner will not assert its rights, to these trademarks and trade names. We do not intend our use or display of other companies’ trade names or trademarks to imply a relationship with, or endorsement or sponsorship of us by, any other companies.

As used in this prospectus, unless the context otherwise requires, the terms “Data I/O,” “the Company,” “we,” “us,” “our” and “our company” mean Data I/O Corporation, a Washington corporation.

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RISK FACTORS

Investing in our securities involves significant risks. Please see the risk factors discussed below, as well as the risk factors under the heading “Item 1A – Risk Factors” in our most recent Annual Report on Form 10-K and in any subsequently-filed Quarterly Reports on Form 10-Q, in addition to those contained in our other filings with the SEC that are incorporated by reference in this prospectus. Before making an investment decision, you should carefully consider these risks as well as other information we include or incorporate by reference in this prospectus. These risks could materially affect our business, financial condition or results of operations and cause the value of our securities to decline. The risks and uncertainties we have described are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also affect our business operations. The occurrence of any of these risks might cause you to lose all or part of your investment in the offered securities.

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, including the documents incorporated by reference herein, contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. This Act provides a “safe harbor” for forward-looking statements to encourage companies to provide prospective information about themselves as long as they identify these statements as forward-looking and provide meaningful cautionary statements identifying important factors that could cause actual results to differ from the projected results. All statements other than statements of historical fact made in this prospectus are forward-looking. In particular, statements herein regarding economic outlook; industry prospects and trends; expected business recovery; industry partnerships; future results of operations or financial position; future spending; expected expenses, breakeven revenue point; expected market decline, bottom or growth; market acceptance of our newly introduced or upgraded products or services; the sufficiency of our cash to fund future operations and capital requirements; development, introduction and shipment of new products or services; changing foreign operations; taxes, trade issues and tariffs; expected inventory levels; expectations for unsupported platform or product versions and related inventory and other charges; supply chain expectations; semiconductor chip shortages and recovery; and any other guidance on future periods are forward-looking statements. Forward-looking statements reflect management’s current expectations and are inherently uncertain. Although we believe that the expectations reflected in these forward-looking statements are reasonable, we cannot guarantee future results, levels of activity, performance, achievements, or other future events. Moreover, neither Data I/O nor anyone else assumes responsibility for the accuracy and completeness of these forward-looking statements. We are under no duty to update any of these forward-looking statements after the date of this prospectus. The Reader should not place undue reliance on these forward-looking statements. The following discussions and the 2025 Annual Report on Form 10-K section entitled “Risk Factors – Cautionary Factors That May Affect Future Results” describe some, but not all, of the factors that could cause these differences.

Any statements that express or involve discussions with respect to predictions, expectations, beliefs, plans, projections, objectives, assumptions or future events or performance (often, but not always, identified by words or phrases such as “expects”, “is expected”, “anticipates”, “believes”, “plans”, “projects”, “estimates”, “assumes”, “intends”, “strategy”, “goals”, “objectives”, “potential”, “possible” or variations thereof or stating that certain actions, events, conditions or results “may”, “could”, “would”, “should”, “might” or “will” be taken, occur or be achieved, or the negative of any of these terms and similar expressions) are not statements of historical fact and may be forward-looking statements.

This list is not exhaustive of the factors that may affect any of our forward-looking statements. Forward-looking statements are statements about the future and are inherently uncertain, and our actual achievements or other future events or conditions may differ materially from those reflected in the forward-looking statements due to a variety of risks, uncertainties and other factors, including, without limitation, those referred to in our Annual Report on Form 10-K for the year ended December 31, 2025 and our subsequent Quarterly Reports on Form 10-Q under the heading “Risk Factors” and Current Reports on Form 8-K and elsewhere.

Our forward-looking statements contained in this prospectus are based on the beliefs, expectations, and opinions of management as of the date of this report. We do not assume any obligation to update forward-looking statements if circumstances or management’s beliefs, expectations or opinions should change, except as required by law. For the reasons set forth above, investors should not place undue reliance on forward-looking statements.

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USE OF PROCEEDS

We are not selling any securities under this prospectus, and we will not receive any proceeds from the sale of shares of our Common Stock by the selling stockholders under this prospectus. All proceeds from the sale of shares of our Common Stock offered by this prospectus will be for the account of the selling stockholders. The selling stockholders will bear all brokerage commissions and similar expenses attributable to the sale of shares under this prospectus, and we will bear all costs, expenses and fees in connection with the registration of such shares.

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SELLING STOCKHOLDERS

The common stock being offered by the selling shareholders are those previously issued to the selling shareholders. For additional information regarding the issuances of those shares of common stock, see “Description of Private Placement” below. We are registering the shares of common stock in order to permit the selling shareholders to offer the shares for resale from time to time. Except for the ownership of the shares of common stock, the selling shareholders have not had any material relationship with us within the past three years.

The table below lists the selling shareholders and other information regarding the beneficial ownership of the shares of common stock by each of the selling shareholders. The second column lists the number of shares of common stock beneficially owned by each selling shareholder, based on the total amount of issued and outstanding common shares of Data I/O Corporation as of July 29, 2026.

In accordance with the terms of a registration rights agreement with the selling shareholders, this prospectus generally covers the resale of the sum of the number of shares of common stock issued to the selling shareholders in the Private Placement (as defined and described below).

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Description of Private Placement

On May 14, 2026, we entered into a securities purchase agreement (the “Securities Purchase Agreement”) with Lytton-Kambara Foundation and Alice W Lytton Family LLC (the “Purchasers”) for the sale and issuance to the Purchasers of securities consisting of the following: 869,840 shares of Common Stock (the “Shares”), convertible debentures in the principal amount of $6,825,400.00 (the “Notes”) and warrants to purchase an aggregate of 1,080,000 shares of common stock (the “Warrants”) (collectively, the “Private Placement”).

On June 17, 2026, we closed the Private Placement, raising gross proceeds of approximately $8.21 million after deducting placement agent fees and other Private Placement expenses payable by us.

Terms of the Note

The five-year Note bears interest at a rate of 4.0% per annum, payable at semiannually on November 1 and May 1, beginning on the first such date after the original issue date of the note, on each conversion date (as to that principal amount then being converted), and on the maturity date. The interest is paid in cash, or at the Company’s option and under certain circumstances, in Preferred Stock. The Investors may convert the Note into Shares of Preferred Stock at the conversion price. The conversion price is $1,000 per share of Preferred Stock. Upon an event of default, the default interest rate increases to 18% per annum. If shareholders approve a proposal that is to be proposed at the Company’s 2026 annual meeting of shareholders, the Note will automatically convert into Preferred Stock.

On July 8, 2026, upon receipt of shareholder approval, the Notes automatically converted into 6,841.33 Series B Convertible Preferred Stock (“Preferred Stock”) in accordance with the terms of the Notes.

Terms of the Series B Convertible Preferred Stock

The Preferred Stock is non-voting, except as required by law. The Preferred Stock accrues dividends at the rate per annum of 4% of the Stated Value of such share, plus the amount of previously accrued dividends, compounded annually, shall accrue on each share then outstanding (the “Accruing Dividends”). Accruing Dividends shall accrue from day to day, whether or not declared, and shall be cumulative. The Stated Value is $1,000 per share. Each share of Preferred Stock shall be convertible into that number of shares of Common Stock (subject to the limitations set forth in the Certificate of Designation relating to limitations on beneficial ownership and the Investor Issuance Cap) determined by dividing the Stated Value plus any Accruing Dividends of such share of Preferred Stock by the Conversion Price. The initial conversion price is $2.50 per share of common stock and it subject to appropriate adjustment in the event of any stock dividend, stock split, combination or other similar recapitalization with respect to the Common Stock. If the principal amount of the Note was converted into Preferred Stock, the Stated Value of the Preferred Stock, without regard to Accruing Dividends of, would be convertible into approximately 2.73 million shares of common stock (subject to the limitations set forth in the Certificate of Designation relating to limitations on beneficial ownership and the Investor Issuance Cap).

Terms of the Warrants

The Warrants are exercisable for an aggregate of 1,080,000 shares of common stock at $3.00 per share for a period of five years. The exercise price is subject to appropriate adjustment in the event of any stock dividend, stock split, combination or other similar recapitalization with respect to the Common Stock.

The Preferred Stock and the Warrants are referred to as the “Convertible Securities.” The Convertible Securities may not be converted or exercised into shares of Common Stock to the extent such conversion or issuance would result in the investor having beneficial ownership of more than 9.99% of then outstanding shares of Common Stock (the “Investors Issuance Cap”).

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The Shares and Convertible Securities were issued in a private placement exempt from the registration requirements of the Securities Act, The Company agreed to file a registration statement with the Securities and Exchange Commission registering the resale of the shares of common stock to be issued in the transaction as well as the common stock issuable upon the exercise of the Warrants and upon conversion of the Preferred Stock.

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PLAN OF DISTRIBUTION

Each selling stockholder of the securities and any of their pledgees, assignees and successors-in-interest may, from time to time, sell any or all of their securities covered hereby on the principal trading market or any other stock exchange, market or trading facility on which the securities are traded or in private transactions. These sales may be at fixed or negotiated prices. A selling stockholder may use any one or more of the following methods when selling securities:

The selling stockholders may also sell securities under Rule 144 or any other exemption from registration under the Securities Act, if available, rather than under this prospectus.

Broker-dealers engaged by the selling stockholders may arrange for other brokers-dealers to participate in sales. Broker-dealers may receive commissions or discounts from the selling stockholders (or, if any broker-dealer acts as agent for the purchaser of securities, from the purchaser) in amounts to be negotiated, but, except as set forth in a supplement to this Prospectus, in the case of an agency transaction not in excess of a customary brokerage commission in compliance with FINRA Rule 2121; and in the case of a principal transaction a markup or markdown in compliance with FINRA Rule 2121.

In connection with the sale of the securities or interests therein, the selling stockholders may enter into hedging transactions with broker-dealers or other financial institutions, which may in turn engage in short sales of the securities in the course of hedging the positions they assume. The selling stockholders may also sell securities short and deliver these securities to close out their short positions, or loan or pledge the securities to broker-dealers that in turn may sell these securities. The selling stockholders may also enter into option or other transactions with broker-dealers or other financial institutions or create one or more derivative securities which require the delivery to such broker-dealer or other financial institution of securities offered by this prospectus, which securities such broker-dealer or other financial institution may resell pursuant to this prospectus (as supplemented or amended to reflect such transaction).

The selling stockholders and any broker-dealers or agents that are involved in selling the securities may be deemed to be “underwriters” within the meaning of the Securities Act in connection with such sales. In such event, any commissions received by such broker-dealers or agents and any profit on the resale of the securities purchased by them may be deemed to be underwriting commissions or discounts under the Securities Act. Each selling stockholder has informed the Company that it does not have any written or oral agreement or understanding, directly or indirectly, with any person to distribute the securities.

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The Company is required to pay certain fees and expenses incurred by the Company incident to the registration of the securities. The Company has agreed to indemnify the selling stockholders against certain losses, claims, damages and liabilities, including liabilities under the Securities Act.

We agreed to keep this prospectus effective until the earlier of (i) the date on which the securities may be resold by the selling stockholders without registration and without regard to any volume or manner-of-sale limitations by reason of Rule 144, without the requirement for the Company to be in compliance with the current public information under Rule 144 under the Securities Act or any other rule of similar effect or (ii) all of the securities have been sold pursuant to this prospectus or Rule 144 under the Securities Act or any other rule of similar effect. The resale securities will be sold only through registered or licensed brokers or dealers if required under applicable state securities laws. In addition, in certain states, the resale securities covered hereby may not be sold unless they have been registered or qualified for sale in the applicable state or an exemption from the registration or qualification requirement is available and is complied with.

Under applicable rules and regulations under the Exchange Act, any person engaged in the distribution of the resale securities may not simultaneously engage in market making activities with respect to the common stock for the applicable restricted period, as defined in Regulation M, prior to the commencement of the distribution. In addition, the selling stockholders will be subject to applicable provisions of the Exchange Act and the rules and regulations thereunder, including Regulation M, which may limit the timing of purchases and sales of the common stock by the selling stockholders or any other person. We will make copies of this prospectus available to the selling stockholders and have informed them of the need to deliver a copy of this prospectus to each purchaser at or prior to the time of the sale (including by compliance with Rule 172 under the Securities Act).

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LEGAL MATTERS

Unless otherwise indicated in the applicable prospectus supplement, the validity of any common stock, preferred stock, debt securities, warrants or units offered under this prospectus and any supplement hereto will be passed upon for us by Dorsey & Whitney LLP, Seattle, Washington.

EXPERTS

The audited financial statements incorporated by reference in this prospectus and elsewhere in the registration statement have been so incorporated by reference in reliance upon the report of Grant Thornton LLP, independent registered public accountants, upon the authority of said firm as experts in accounting and auditing.

INCORPORATION BY REFERENCE

The SEC’s rules allow us to “incorporate by reference” information into this prospectus, which means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is deemed to be part of this prospectus, and subsequent information that we file with the SEC will automatically update and supersede that information. Any statement contained in this prospectus or a previously filed document incorporated by reference will be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus or a subsequently filed document incorporated by reference modifies or replaces that statement.

We incorporate by reference in this prospectus our documents listed below and any future filings made by us with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, between the date of this prospectus and the termination of the offering of the securities described in this prospectus. We are not, however, incorporating by reference any documents or portions thereof, whether specifically listed below or filed in the future, that are not deemed “filed” with the SEC, including any Compensation Committee report, any performance graph or any information furnished pursuant to Items 2.02 or 7.01 of Form 8-K or related exhibits furnished pursuant to Item 9.01 of Form 8-K.

This prospectus and any accompanying prospectus supplement incorporate by reference the documents set forth below that have previously been filed with the SEC:

All filings filed by us pursuant to the Exchange Act after the date of the initial filing of the registration statement of which this prospectus forms a part and prior to the effectiveness of such registration statement (excluding

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information furnished pursuant to Items 2.02, 7.01 and 9.01 of Form 8-K or any other information that is identified as “furnished” rather than filed) shall also be deemed to be incorporated by reference into this prospectus.

Any statement contained in this prospectus or in any document incorporated or deemed to be incorporated by reference into this prospectus will be deemed modified or superseded for the purposes of this prospectus to the extent that a statement contained in this prospectus or any subsequently filed document which also is, or is deemed to be, incorporated by reference into this prospectus modifies or supersedes that statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus.

You can obtain any of the filings incorporated by reference in this prospectus through us or from the SEC through the SEC’s website at www.sec.gov. Our filings with the SEC, including our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, and exhibits incorporated in and amendments to those reports, are also available free of charge on our website (www.dataio.com) as soon as reasonably practicable after they are filed with, or furnished to, the SEC. Information on, or accessible through, our website is not part of this prospectus, nor is such content incorporated by reference herein, and should not be relied upon in determining whether to make an investment in our securities. You can obtain any of the documents incorporated by reference into this prospectus from us without charge, excluding any exhibits to those documents unless the exhibit is specifically incorporated by reference into those documents. You can obtain documents incorporated by reference into this prospectus by requesting them in writing or by telephone from us at the following address:

DATA I/O CORPORATION

Attn: Vice President and Chief Financial Officer

6645 185th Ave N.E., Suite 100

Redmond, Washington 98052

(425) 881-6444

DISCLOSURE OF COMMISSION POSITION ON INDEMNIFICATION FOR SECURITIES ACT LIABILITIES

Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers or persons controlling the registrant, the registrant has been informed that in the opinion of the SEC such indemnification is against public policy as expressed in the Securities Act and is therefore unenforceable.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus is part of a registration statement on Form S-1 that we have filed with the SEC. This prospectus omits some of the information contained in the registration statement, and we refer you to the full registration statement for further information about us and the securities being offered by the selling stockholders under this prospectus. Before making an investment decision, you should read, in addition to this prospectus and the registration statement, any documents that we incorporate by reference in this prospectus, as referred to under “Incorporation By Reference.”

We file reports, proxy statements and other information with the SEC. The SEC maintains a website that contains reports, proxy and information statements and other information about issuers, such as us, who file electronically with the SEC. The address of that website is http://www.sec.gov.

Our website address is www.dataio.com. Information contained on, or that can be accessed through, our website is not incorporated by reference into this prospectus, and you should not consider information on our website to be part of this prospectus. We have included our website address as an inactive textual reference only.

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Prospectus

4,686,371 Shares of Common Stock

August 12, 2026