6-K - ZTO Express (Cayman) Inc. (0001677250) (Filer)

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 UNDER

THE SECURITIES EXCHANGE ACT OF 1934

For the month of October 2026

Commission File Number: 001-37922

ZTO Express (Cayman) Inc.

Building One, No. 1685 Huazhi Road

Qingpu District

Shanghai, 201708

People’s Republic of China

(Address of principal executive offices)

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

Form 20-F x Form 40-F ¨

Exhibit Index

Exhibit 99.1 — Next Day Disclosure Return Dated September 29, 2026

Exhibit 99.2 — Next Day Disclosure Return Dated September 30, 2026

Exhibit 99.3 — Next Day Disclosure Return Dated October 2, 2026

Exhibit 99.4 — Next Day Disclosure Return Dated October 2, 2026

Exhibit 99.5 — Monthly Return for Equity Issuer and Hong Kong Depositary Receipts listed under Chapter 19B of the Exchange Listing Rules on Movements in Securities

Exhibit 99.6 — Next Day Disclosure Return Dated October 5, 2026

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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.

Date: October 5, 2026

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