Supaul is a district located in the state of Bihar, India. It is situated in the northeastern part of the state and is known for its agricultural activities. The district headquarters is also named Supaul.

Supaul district shares its borders with the neighboring districts of Madhepura in the south, Araria in the west, and Saharsa in the east. The district is traversed by the river Kosi, which is known as the "Sorrow of Bihar" due to its frequent flooding. The Kosi River brings both benefits and challenges to the region.