UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-A

FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES

PURSUANT TO SECTION 12(b) OR (g) OF THE

SECURITIES EXCHANGE ACT OF 1934

BondBloxx ETF Trust

(Exact name of registrant as specified in its charter)

Securities to be registered pursuant to Section 12(b) of the Act:

If this form relates to the registration of a class of securities pursuant to Section 12(b) of the Exchange Act and is effective pursuant to General Instruction A.(c) or (e), check the following box. ☒

If this form relates to the registration of a class of securities pursuant to Section 12(g) of the Exchange Act and is effective pursuant to General Instruction A.(d) or (e), check the following box. ☐

If this form relates to the registration of a class of securities concurrently with a Regulation A offering, check the following box. ☐

Securities Act registration statement or Regulation A offering statement file number to which this form relates: 333-258986 (if applicable)

Securities to be registered pursuant to Section 12(g) of the Act: None

Item 1. Description of Registrant’s Securities to be Registered.

A description of the shares of beneficial interest, no par value, of BondBloxx Core Plus ETF (the “Shares”) is set forth in Post-Effective Amendment No. 85 to the Registrant’s Registration Statement on Form N-1A (“Registration Statement”) (Commission File Nos. 333-258986; 811-23731), as filed with the Securities and Exchange Commission (“SEC”) on October 20, 2026, which description is incorporated herein by reference. Any amendment or form of supplement to the Registration Statement that is subsequently filed with the SEC that relates to the Shares is hereby also incorporated by reference herein.

Item 2. Exhibits.

SIGNATURE

Pursuant to the requirements of Section 12 of the Securities Exchange Act of 1934, the registrant has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereto duly authorized, as of this 28th day of October, 2026.