Khemarat (Thai: เขมราฐ) is the northernmost district (amphoe) of Ubon Ratchathani province, northeastern Thailand.

During the Thesaphiban reforms at the beginning of the 20th century it became subordinate to Ubon Ratchathani.

Neighboring districts are (from the southeast clockwise) Na Tan, Pho Sai, and Kut Khaopun of Ubon Ratchathani Province, Pathum Ratchawongsa and Chanuman of Amnat Charoen province.

The district is divided into nine sub-districts (tambons), which are further subdivided into 117 villages (mubans).

Missing numbers belong to tambon which now form Na Tan District.