Khao Chaison (Thai: เขาชัยสน, pronounced [kʰǎw t͡ɕʰāj.sǒn]) is a district (amphoe) of Phatthalung province, southern Thailand.

Neighboring districts are (from the south clockwise) Bang Kaeo, Tamot, Kong Ra, and Mueang Phatthalung of Phatthalung Province, Krasae Sin of Songkhla province.

[3] In 1940, the minor district was then renamed Khao Chaison to match the central tambon.

[5] The district is divided into five sub-districts (tambons), which are further subdivided into 56 villages (mubans).

Missing numbers are tambon which now form Bang Kaeo District.