April 28, 2020

State Street Bank and Trust Company

Josiah Quincy Building

200 Newport Avenue

North Quincy, Massachusetts 02171

Location Code: JQB5

Attention: Russell M. Donohoe

Re: Transfer Agency and Service Agreement - New Portfolios

Ladies and Gentlemen:

Please be advised that the undersigned Trust has established two (2) new series of shares to be known as:

American Century ETF Trust - American Century Mid Cap Growth Impact ETF

American Century ETF Trust - American Century Sustainable Equity ETF (the “New Portfolios”).

In accordance with Section 12, the Additional Trusts and Portfolios provision, of the Transfer Agency and Service Agreement dated as of January 9, 2018 (the “Transfer Agency Agreement”) by and among each Trust party thereto and State Street Bank and Trust Company, the undersigned Trust hereby requests that your bank act as Transfer Agent for the respective New Portfolios under the terms of the Transfer Agent Agreement. In connection with such request, the undersigned Trust hereby confirms to you, as of the date hereof, its representations and warranties set forth in Section 4 of the Transfer Agent Agreement. Capitalized terms used herein without definition shall have the meanings ascribed to them in the Transfer Agent Agreement.

Kindly indicate your acceptance of the foregoing by executing this letter agreement and returning a copy to the Trust.

Sincerely,

American Century Investment Management, Inc. on behalf of

American Century ETF Trust - American Century Mid Cap Growth Impact ETF

American Century ETF Trust - American Century Sustainable Equity ETF

By:    /s/ Otis H. Cowan

Name:    Otis H. Cowan

Title:    Vice President, Duly Authorized

Agreed and Accepted:

STATE STREET BANK AND TRUST COMPANY

By: /s/ Andrew Erickson

Name: Andrew Erickson

Title: Executive Vice President

Effective Date: May 6, 2020

American Century Investments

P.O. Box 410141, 4500 Main Streetamericancentury.comCorporate Headquarters: Kansas City, MO

Kansas City, MO 64141-0141800-345-2021 or 816-531-5575