Mesocco Castle is a ruined castle in the municipality of Mesocco of the Canton of Graubünden in Switzerland. It is a Swiss heritage site of national significance.

The Castello ruins are among the largest in the canton. Originally the seat of the noble family von Sax, from the 12th century until 1480 it was held by the Freiherr of Misox/Mesocco. From 1480 until 1549 it was held by the Trivulzio family.

A small fortified church, the Church of S. Carpoforo, was built on the hill top around the 7th century as a refuge castle for the surrounding villages.