The Warsaw West County (Polish: powiat warszawski zachodni) is a county in Masovian Voivodeship, located in the east-central Poland, with its seat of government located in Ożarów Mazowiecki. Other towns located in the county are: Łomianki, and Błonie. 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 square kilometres (205.8 sq mi). As of 2019 its total population is 117,783, out of which the population of Łomianki is 17,022, that of Błonie is 12,231, that of Ożarów 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.
The county is subdivided into seven gminas (three urban-rural and four rural). These are listed in the following table, in descending order of population.