Ko Phra Thong (Thai: เกาะพระทอง, pronounced [kɔ̀ʔ pʰráʔ tʰɔːŋ]) is an island in Khura Buri District, Phang Nga Province, southern Thailand on the Andaman Sea.

It has an area of 88 square kilometres (34 sq mi) and is separated from the mainland by a seven-metre-deep (23 ft) canal.

There have always been a number of special natural features of Ko Phra Thong Island.

These villages total fewer than 300 inhabitants consisting of Moken, a tribe of sea gypsies, and Thais.

The island is part of the Mu Ko Ra–Ko Phra Thong National Park, established in 2001.