Prospectus Certification by Investment Company (Form 497J)

May 4, 2026

VIA ELECTRONIC FILING

Securities and Exchange Commission

100 F Street, N.E.

Washington, D.C. 20549

Attention: Division of Investment Management

RE: BlackRock LifePath^® Index Retirement Fund, BlackRock LifePath^® Index 2030

Fund, BlackRock LifePath^® Index 2035 Fund, BlackRock LifePath^® Index 2040 Fund,

BlackRock LifePath^® Index 2045 Fund, BlackRock LifePath^® Index 2050 Fund,

BlackRock LifePath^® Index 2055 Fund, BlackRock LifePath^® Index 2060 Fund,

BlackRock LifePath^® Index 2065 Fund, and BlackRock LifePath^® Index 2070 Fund,

each a series of BlackRock Funds III

Post-Effective Amendment No. 411 to the Registration Statement on Form N-1A

(Securities Act File No. 33-54126, Investment Company Act File No. 811-07332)

Ladies and Gentlemen:

Pursuant to Rule 497(j) under the Securities Act of 1933, as amended (the "1933 Act"), BlackRock Funds III (the "Registrant"), on behalf of its series BlackRock LifePath^® Index Retirement Fund, BlackRock LifePath^® Index 2030 Fund, BlackRock LifePath^® Index 2035 Fund, BlackRock LifePath^® Index 2040 Fund, BlackRock LifePath^® Index 2045 Fund, BlackRock LifePath^® Index 2050 Fund, BlackRock LifePath^® Index 2055 Fund, BlackRock LifePath^® Index 2060 Fund, BlackRock LifePath^® Index 2065 Fund, and BlackRock LifePath^® Index 2070 Fund (the "Funds"), hereby certifies that:

(1) the form of Prospectuses and Statement of Additional Information that would have been filed pursuant to Rule 497(c) under the 1933 Act would not have differed from that contained in Post-Effective Amendment No. 411 to the Registration Statement on Form N-1A of the Registrant with respect to the Funds; and

(2) the text of Post-Effective Amendment No. 411 to the Registration Statement on Form N-1A of the Registrant with respect to the Funds was filed electronically with the Securities and Exchange Commission on April 30, 2026.