The diocese of Lạng Sơn and Cao Bằng (Latin: Dioecesis Langsonensis et Caobangensis) is a Roman Catholic diocese in northern Vietnam's Lạng Sơn and Cao Bằng provinces.

Joseph Chau Ngoc Tri (vn) was appointed in 2016 as the diocese's bishop.

[5] The creation of the diocese in its present form was declared on 24 November 1960.

[7] In June 2007, fifty deacons were officially ordained in Lạng Sơn.

This article on a Roman Catholic diocese in Vietnam is a stub.