Mažeikiai District Municipality (Lithuanian: Mažeikių rajono savivaldybė, Samogitian: Mažėikiu rajuona savivaldībė) is located in the north-west of Lithuania, on the River Venta in Telšiai County.

Of this number, 46,223 live in towns and 21,170 in villages.

Mažeikiai District stretches for 43.5 km (27.0 mi) east-to-west and 38 km (24 mi) north-to-south.

Petraičiai village is the westernmost settlement, with Kalniškiai and Pakliaupė villages being the easternmost settlements.

The northernmost is Giniočiai, while the southernmost is Pasruojė.