Mrągowo County (Polish: powiat mrągowski) is a unit of territorial administration and local government (powiat) in Warmian-Masurian Voivodeship, northern Poland. It was created on January 1, 1999 as a result of the Local Government Reorganization Act of 1998. Its administrative seat and largest town is Mrągowo, which lies 54 kilometres (34 mi) east of the regional capital Olsztyn. The only other town in the county is Mikołajki, lying 21 km (13 mi) east of Mrągowo.
The county covers an area of 1,065.23 square kilometres (411.3 sq mi). As of 2006 its total population is 50,087, out of which the population of Mrągowo is 21,772, that of Mikołajki is 3,848, and the rural population is 24,467.
The county is subdivided into five gminas (one urban, one urban-rural and three rural). These are listed in the following table, in descending order of population.