Baulkham Hills is a suburb in the Hills District of Greater Sydney, in the state of New South Wales, Australia. It is located within 30 kilometres north-west of the Sydney central business district mostly within the local government area of The Hills Shire, of which Baulkham Hills was formerly the administrative seat and namesake of The Hills Shire. A small section of the suburb which is located south of the Hills Motorway-Windsor Road intersection is part of the City of Parramatta.

The Hills Shire is a local government area in the Greater Sydney region of Sydney, New South Wales, Australia. The area is north-west of the Sydney central business district, and encompasses 401 square kilometres (155 sq mi) stretching from the M2 Hills Motorway in the south to Wisemans Ferry on the Hawkesbury River in the north. The Hills Shire had a population of 191,876 as of the 2021 census.