Khamcha-i (Thai: คำชะอี) is a district (amphoe) of Mukdahan province, northeastern Thailand.

Neighboring districts are (from the north clockwise) Dong Luang, Mueang Mukdahan, and Nong Sung of Mukdahan Province; Kuchinarai and Khao Wong of Kalasin province.

The minor district (king amphoe) was created on 24 June 1941, when the six tambons Khamcha-i, Nong Sung, Ban Song, Ban Kho, Ban Lao, and Nong Ian were split off from Mukdahan District.

The district is divided into nine sub-districts (tambons), which are further subdivided into 87 villages (muban).

Missing numbers are tambon which now form Nong Sung District.