The Zengwen River is the fourth longest river in Taiwan after the Zhuoshui River, Gaoping, and Tamsui, with a total length of about 146 km (91 mi). It flows through Tainan and Chiayi County.It is located in the southwestern part of the island.

Zéngwén is the pinyin romanization of the Mandarin pronunciation of the river's Chinese name 曾文溪. The river was formerly known as the Tsan-bun from the Hokkien pronunciation of the same name.

It was formerly known as the Taiwanfu from a former name of Tainan, when it was the headquarters of Qing administration on the island as a district of Fujian Province.

The largest reservoir in Taiwan, Zengwen Reservoir, formed by Zengwen Dam, is located Located upstream of Zengwen River.

Taijiang National Park encompasses parts of the Zengwen estuary as well as nearby coastal areas. The endangered black-faced spoonbills come every winter as migrants and inhabit downstream near the estuary, where many other waterfowls are also found. A conservation area has been set up to protect the spoonbills.

• List of rivers in Taiwan