Nong Saeng (Thai: หนองแสง, pronounced [nɔ̌ːŋ sɛ̌ːŋ]) is a district (amphoe) of Udon Thani province, northeastern Thailand.

Neighboring districts are (from the west clockwise) Nong Wua So, Mueang Udon Thani, Kumphawapi, and Non Sa-at of Udon Thani Province, and Khao Suan Kwang of Khon Kaen province.

It was made a minor district (king amphoe) on 1 January 1981,[1] then consisting of two tambons and 27 villages.

The district office was opened in village three of tambon Nong Saeng on 1 January 1983.

[2] The district is divided into four sub-districts (tambons), which are further subdivided into 38 villages (mubans).