Prospectus Certification by Investment Company (Form 497J)

December 15, 2025

VIA EDGAR TRANSMISSION

U.S. Securities and Exchange Commission

Division of Investment Management

100 F Street, NE

Washington, DC 20549

Re: Themes ETF Trust (the "Trust")

File Nos.: 333-271700 and 811-23872

Leverage Shares 2X Long IREN Daily ETF

Leverage Shares 2X Long BE Daily ETF

Leverage Shares 2X Long GEV Daily ETF

Leverage Shares 2X Long SATS Daily ETF

Leverage Shares 2X Long NIO Daily ETF

Leverage Shares 2X Long SNAP Daily ETF

Leverage Shares 2X Long BIDU Daily ETF

Ladies and Gentlemen:

Pursuant to Rule 497(j) under the Securities Act of 1933, as amended, and the regulations thereunder, the Trust on behalf of its series, Leverage Shares 2X Long IREN Daily ETF, Leverage Shares 2X Long BE Daily ETF, Leverage Shares 2X Long GEV Daily ETF, Leverage Shares 2X Long SATS Daily ETF, Leverage Shares 2X Long NIO Daily ETF, Leverage Shares 2X Long SNAP Daily ETF, and Leverage Shares 2X Long BIDU Daily ETF, hereby certifies that the form of Prospectus and Statement of Additional Information that would have been filed under Rule 497(b) or (c) would not have differed from those contained in Post-Effective Amendment No. 81 to the Trust's Registration Statement on Form N-1A, filed on December 11, 2025.

If you have any questions or require further information, please contact Karen Aspinall at (949) 629-3928 or [email protected].

Sincerely,

/s/ Karen Aspinall

Karen Aspinall

KAREN A. ASPINALL ● PARTNER

11300 Tomahawk Creek Pkwy ● Ste. 310 ● Leawood, KS 66211 ● p: 949.629.3928

Practus, LLP ● [email protected] ● Practus.com