Olsztyn County (Polish: powiat olsztyński) is a unit of territorial administration and local government (powiat) in Warmian-Masurian Voivodeship, northern Poland.

It came into being on January 1, 1999, as a result of the Polish local government reforms passed in 1998.

The county covers an area of 2,840.29 square kilometres (1,096.6 sq mi).

The county is subdivided into 12 gminas (five urban-rural and seven rural).

These are listed in the following table, in descending order of population.