ZTO 6-K

UNITED STATES

SECURITIES AND EXCHANGECOMMISSION

WASHINGTON, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATEISSUER

PURSUANT TO RULE 13a-16OR 15d-16 UNDER

THE SECURITIES EXCHANGE ACT OF 1934

For the month of December 2025

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 ¨

Resignation of Mr. Kao

ZTO Express (Cayman) Inc. (the “Company”) announced that Mr. Tsun-Ming Daniel Kao has tendered his resignation as an independent director of the board of directors of the Company (the “Board”) and a member of the nominating and corporate governance committee of the Board, due to his plan to commit more time on other professional endeavors, effective December 31, 2025. Mr. Kao’s resignation was not due to any disagreement with the Board or the Company. The Company extends its sincere gratitude to Mr. Kao’s service and wishes him the best in his future endeavors.

Exhibit Index

Exhibit 99.1 – Announcement—Resignation of Independent Non-executive Director

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: December 31, 2025

Exhibit 99.1

HongKong Exchanges and Clearing Limited and The Stock Exchange of Hong Kong Limited take no responsibility for the contents of this announcement,make no representation as to its accuracy or completeness and expressly disclaim any liability whatsoever for any loss howsoever arisingfrom or in reliance upon the whole or any part of the contents of this announcement.

Underour weighted voting rights structure, our share capital comprises Class A ordinary shares and Class B ordinary shares. EachClass A ordinary share entitles the holder to exercise one vote, and each Class B ordinary share entitles the holder to exercise10 votes, respectively, on all matters that require a shareholder’s vote. Shareholders and prospective investors should be awareof the potential risks of investing in a company with a weighted voting rights structure. Our American depositary shares, each representingone of our Class A ordinary shares, are listed on the New York Stock Exchange in the United States under the symbol ZTO.

ZTOExpress (Cayman) Inc.

中通快遞（開曼）有限公司

(Acompany controlled through weighted voting rights and incorporated in the Cayman Islands with limited liability)

(StockCode: 2057)

RESIGNATIONOF INDEPENDENT NON-EXECUTIVE DIRECTOR

The board (the “Board”) of directors of ZTO Express (Cayman) Inc. (the “Company”) hereby announces that, Mr. Tsun-Ming (Daniel) KAO (高遵明) (“Mr. KAO”) has tendered his resignation as an independent non-executive director of the Company and a member of the nominating and corporate governance committee of the Board, due to his plan to commit more time on other professional endeavors, effective December 31, 2025.

Mr. KAO has confirmed that he has no disagreement with the Board and there is no matter in respect of his resignation that needs to be brought to the attention of the shareholders of the Company or The Stock Exchange of Hong Kong Limited.

The Company extends its sincere gratitude to Mr. KAO’s service and wishes him the best in his future endeavors.

Hong Kong, December 31, 2025

Asat the date of this announcement, the Board comprises Mr. Meisong LAI as the chairman and executive director, Mr. Jilei WANGand Mr. Hongqun HU as executive directors, Mr. Xing LIU and Ms. Di XU as non-executive directors, Mr. Frank ZhenWEI, Mr. Qin Charles HUANG, Mr. Herman YU and Ms. Fang XIE as independent non-executive directors.