Mažeikiai District Municipality is located in the north-west of Lithuania, on the River Venta in Telšiai County. The administrative center of Mažeikiai District is the city of Mažeikiai. Its territory of 1,220.2 km2 (471.1 sq mi) is composed of 32 km2 (12 sq mi) of towns and settlements, 22 km2 (8.5 sq mi) of industrial enterprises and roads, 614 km2 (237 sq mi) of agricultural lands, 273 km2 (105 sq mi) of forests, and 68 km2 (26 sq mi) of tracts of other designation. There is one urban and 8 rural elderates. In 2003, the population was 67,393. Of this number, 46,223 live in towns and 21,170 in villages.

Mažeikiai is a city in northwestern Lithuania, on the Venta River. It has a population of around 32,000, making it the eighth largest city in Lithuania. The city is the administrative center of Mažeikiai district municipality in Telšiai County. It is the largest city that does not have its own county.