The Warsaw West County (powiat warszawski zachodni) is a county in Masovian Voivodeship, located in the east-central Poland, with its seat of government located in O?arów Mazowiecki. Other towns located in the county are: ?omianki, and B?onie. It was established on January 1, 1999, as a result of the Polish local government reforms. Until 31 December 2005, its seat was located extraterritorially in the city of Warsaw.
The county covers an area of 532.99 km2. As of 2019 its total population is 117,783, out of which the population of ?omianki is 17,022, that of B?onie is 12,231, that of O?arów Mazowiecki is 11,719, and the rural population is 76,781.
Warsaw West County is bordered by Nowy Dwór County and Legionowo County to the north, the city of Warsaw to the east, Pruszków County to the south, Grodzisk County to the south-west, and Sochaczew County to the west.
