Jacetania (Aragonese: Chacetania) is a comarca in northern Aragon, Spain. It is located in the northwestern corner of the Huesca and Zaragoza provinces. The administrative capital is Jaca, with 13,374 inhabitants the largest town of the comarca. The area is famous for its ski resorts.

Jacetania borders with France in the north and with Navarre in the west. Most of its territory is mountainous, with the ranges of the Pyrenees and Pre-Pyrenees covering most of its area. The name of the comarca originates in the ancient Iberian tribe of the Iacetani (Latin: Iaccetani). The Aragonese language is spoken in this comarca, in particular, its variety, Jaca Aragonese.

This comarca was the birthplace of the historic County of Aragon.

The traditional names of the towns, when different from the official name, are in brackets.