Ranong is one of Thailand's southern provinces (changwat), on the west coast along the Andaman Sea. It has the fewest inhabitants of all Thai provinces. provinces neighboring Ranong are (clockwise) Chumphon, Surat Thani, and Phang Nga. To the west, it borders Kawthaung, Tanintharyi, Myanmar.

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.