Macarthur is a region in the south-west part of the Greater Sydney area, in the state of New South Wales, Australia. The region includes the local government areas of the City of Campbelltown, Camden Council, and Wollondilly Shire. It covers an area of 3,067 square kilometres and has a population of close to 310,000 residents. The region geographically forms the foothills between the Blue Mountains and Southern Highlands regions.

Sydney is the capital city of the state of New South Wales and the most populous city in Australia. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about 80 km from the Pacific Ocean in the east to the Blue Mountains in the west, and about 80 km from the Ku-ring-gai Chase National Park and the Hawkesbury River in the north and north-west, to the Royal National Park and Macarthur in the south and south-west. Greater Sydney consists of 658 suburbs, spread across 33 local government areas. Residents of the city are colloquially known as "Sydneysiders". The estimated population in June 2023 was 5,450,496, which is about 66% of the state's population. The city's nicknames include the "Emerald City" and the "Harbour City".