Exhibit (g)(9)

AMENDMENT TO CUSTODIAN AGREEMENT

THIS AMENDMENT TO CUSTODIAN AGREEMENT (this “Amendment”) is made as of March 13, 2025 by and between BROWN BROTHERS HARRIMAN & CO., a New York limited partnership (“BBH&Co.”) and BONDBLOXX ETF TRUST, a Delaware statutory trust (the “Fund”) on behalf of each series, separately and not jointly, listed on Annex A to the Agreement as may be amended from time to time. All capitalized terms used but not defined herein shall have the meanings set forth in the Agreement.

WHEREAS, BBH&Co. and the Fund are Parties to a Custodian Agreement dated as of November 29, 2021, as amended (the “Agreement”); and

WHEREAS, in accordance with Section 12 of the Agreement, the Parties desire to amend the Agreement.

NOW, THEREFORE, in consideration of the mutual agreements herein contained and other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged by the parties, each of the parties hereto hereby agree as follows:

1. Annex A to the Agreement is hereby deleted in its entirety and replaced with the attached updated Annex A.

2. As amended hereby, all terms and provisions of the Agreement are hereby ratified and affirmed as of the date hereof and are hereby extended to give effect to the terms hereof.

3. This Amendment, together with the Agreement, constitutes the entire agreement of the parties with respect to its subject matter and supersedes all oral communications and prior writings with respect hereto. Except as expressly modified hereby, the Agreement shall continue in full force and effect in accordance with its terms and conditions.

4. This Amendment may be executed in any number of counterparts each of which shall be deemed to be an original, but all of which together shall constitute one and the same Amendment.

5. This Amendment shall be construed in accordance the governing law and exclusive jurisdiction provisions of the Agreement.

[Signature Page Follows]

IN WITNESS WHEREOF, each of the undersigned parties has executed this Amendment to the Agreement effective as of the date first above written.

ANNEX A

TO

CUSTODIAN AGREEMENT

LIST OF FUNDS

Updated as of March 13, 2025

The following is a list of Funds for which BBH shall serve under the Custodian Agreement: