Thon Buri (Thai: ธนบุรี, pronounced [tʰōn būrīː]) is one of the 50 districts (khet) of Bangkok, Thailand.

Neighboring districts are (from north clockwise) Bangkok Yai, Phra Nakhon (across Chao Phraya River), Khlong San, Bang Kho Laem (across Chao Phraya), Rat Burana, Chom Thong, and Phasi Charoen.

In addition to the native inhabitants, the district was settled relatively early by foreigners, first Chinese merchants, then the Portuguese after the fall of Ayutthaya to the Burmese in 1767.

In addition to the Chinese and Portuguese, there were also Muslims and Mon, from Burma, as well as French priests, particularly in the neighbourhood called Kudi Chin.

It was renamed Bang Yi Ruea on 11 July 1916 (after the location of the new district office), and finally Thon Buri on 17 April 1939.