UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16

of the Securities Exchange Act of 1934

For the month of September 2026

Commission File Number: 001-37643

PURPLE BIOTECH LTD.

(Translation of registrant’s name into English)

4 Oppenheimer Street, Science Park, Rehovot 7670104, Israel

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

Form 20-F ☒ Form 40-F ☐

Purple Biotech

On September 2, 2026, Purple Biotech Ltd. (the “Registrant”) issued a press release “New U.S. Patent Allowance Strengthens Protection for CAPTN-3 Modular Platform for Next-Generation Multispecific Antibodies”, which is attached hereto as Exhibit 99.1.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.