Form 485BXT PUTNAM INVESTMENT FUNDS

This Post-Effective Amendment No. 196 is being filed pursuant to Rule 485(b) under the Securities Act of 1933, as amended (the “Securities Act”), solely to designate March 21, 2018, as the new effective date for Post-Effective Amendment No. 193 filed pursuant to Rule 485(a) under the Securities Act on January 18, 2018. This Post-Effective Amendment No. 196 is not intended to amend or supersede any information contained in Post-Effective Amendment No. 193.

This Post-Effective Amendment relates solely to the Registrant’s Putnam Sustainable Future Fund (formerly Putnam Multi-Cap Value Fund) series. Information contained in the Registrant's Registration Statement relating to any other series of the Registrant is neither amended nor superseded hereby.

Part A. INFORMATION REQUIRED IN A PROSPECTUS

Part A is incorporated by reference to Part A of Post-Effective Amendment No. 193 to the Registration Statement on Form N-1A of Putnam Investment Funds (the “Registrant”) under the Securities Act of 1933, as amended, and Amendment No. 191 to the Registrant’s Registration Statement on Form N-1A under the Investment Company Act of 1940, as amended, filed with the Securities and Exchange Commission (the “SEC”) on January 18, 2018 (“Amendment No. 193/191”).

Part B. INFORMATION REQUIRED IN A STATEMENT OF ADDITIONAL INFORMATION

Part B is incorporated by reference to Part B of Amendment No. 193/191 to the Registrant’s Registration Statement on Form N-1A filed with the SEC on January 18, 2018.

Part C. OTHER INFORMATION

Part C is incorporated by reference to Part C of Amendment No. 193/191 to the Registrant’s Registration Statement on Form N-1A filed with the SEC on January 18, 2018.

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this Registration Statement under Rule 485(b) under the Securities Act of 1933, as amended, and the Registrant has duly caused this Amendment to its Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of Boston, and The Commonwealth of Massachusetts, on the 16^th day of March, 2018.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to the Registration Statement has been signed below by the following persons in the capacities and on the date indicated: