The arrondissement of Castelsarrasin is an arrondissement of France in the Tarn-et-Garonne department in the Occitania region.

[2] Its population is 78,979 (2021), and its area is 1,601.5 km2 (618.3 sq mi).

[3] The communes of the arrondissement of Castelsarrasin, and their INSEE codes, are:[2] The arrondissement of Castelsarrasin was created in 1800 as part of the department Haute-Garonne.

[5] As a result of the reorganisation of the cantons of France which came into effect in 2015, the borders of the cantons are no longer related to the borders of the arrondissements.

The cantons of the arrondissement of Castelsarrasin were, as of January 2015:[6]