Pa Daet (Thai: ป่าแดด; IPA: [pàː dɛ̀ːt]) is a district (amphoe) in the southern part of Chiang Rai province, northern Thailand.

The area of Pa Daet was originally dense forest of the Phan district.

[2] Neighboring districts are (from the west clockwise): Phan, Mueang Chiang Rai, and Thoeng of Chiang Rai Province; Chun, Dok Khamtai, Phu Kamyao, Mueang Phayao, and Mae Chai of Phayao province.

The Phi Pan Nam Mountains dominate the landscape of the district.

The district is divided into five sub-districts (tambons), which are further subdivided into 58 villages (mubans).