The Pran Buri River (Thai: แม่น้ำปราณบุรี, RTGS: Maenam Pran Buri, Thai pronunciation: [mɛ̂ːnáːm praːn buriː]) is a river in the Prachuap Khiri Khan Province, Thailand, on the Kra Isthmus of the Malay Peninsula. The Pran Buri river originates in southern part of the Kaeng Krachan National Park in the Tenasserim Hills and after 130 km mouths into the Gulf of Thailand. The only town at the river course is Pranburi, the center of the Pran Buri district. The watershed of the Pran Buri River has an area of about 2000 km².
The Pran Buri dam was built in 1978, to protect the lowland against flooding and well as to have a steady waterflow for irrigation use. The 42 m high and 1500 m wide earthen dam creates an artificial lake, which covers an area of 35.2 km² and has a capacity of 445 million m³.
At the estuary of the river to the Gulf of Thailand is the Pran Buri Forest Park, covering 3.17 km² of mixed forest and mangrove forest. It was created in 1982.