Montesquiu is a municipality in the comarca of Osona in Catalonia, Spain. It lies on the banks of the Ter river in the north of the comarca. The municipality became part of Osona in the comarcal revision of 1990; before that, it formed part of Ripollès.
Montesquiu sits on the main communication route between Barcelona and Puigcerdà. It is served by the N-152 road and by a station on the Renfe railway line.
The municipality's thirteenth-century castle is used for cultural events during the summer.