Si Nakhon (Thai: ศรีนคร, pronounced [sǐː ná(ʔ).kʰɔ̄ːn]) is a district (amphoe) of Sukhothai province, in the lower northern region of Thailand.

Neighboring districts are (from the south clockwise): Sawankhalok and Si Satchanalai of Sukhothai Province, and Tron and Phichai of Uttaradit province.

The minor district (king amphoe) Si Nakhon was established on 20 January 1976, then consisting of the two tambons: Si Sakhon and Nakhon Doet of Sawankhalok district.

[4] The district is divided into five sub-districts (tambons), which are further subdivided into 49 villages (mubans).

This Sukhothai Province location article is a stub.