The City of Sydney is the local government area covering the Sydney central business district and surrounding inner city suburbs of the greater metropolitan area of Sydney, New South Wales, Australia. Established by Act of Parliament in 1842, the City of Sydney is the oldest, and the oldest-surviving, local government authority in New South Wales, and the second-oldest in Australia, with only the City of Adelaide being older by two years.

Local government is the third-level of government in Australia, administered with limited autonomy under the states and territories, and in turn beneath the federal government. Local government is not mentioned in the Constitution of Australia, and two referendums in 1974 and 1988 to alter the Constitution relating to local government were unsuccessful. Every state/territory government recognises local government in its own respective constitution. Unlike the two-tier local government system in Canada or the United States, there is only one tier of local government in each Australian state/territory, with no distinction between counties and cities.