Chumphon is a southern province (changwat) of Thailand on the Gulf of Thailand. Neighbouring provinces are Prachuap Khiri Khan, Surat Thani, and Ranong. To the west it borders the Burmese province of Tanintharyi.

The provinces of Thailand are administrative divisions of the government of Thailand. The country is divided into 76 provinces proper, with one additional special administrative area. They are the primary local government units and act as juristic persons. They are divided into amphoe (districts) which are further divided into tambon, the next lower level of local government.