The council has many of the functions, duties and powers of a district council and of a regional council,[3] making it in effect a unitary authority with slightly fewer responsibilities than other unitary authorities.

The Chatham Islands was incorporated into the Colony of New Zealand by the British in 1842.

[4] Chatham Islands County was established in 1901,[5][6] though the Chatham Islands County Council was not established until 1926.

[7][8] Succeeding the county council, the Chatham Islands Council was established by the Chatham Islands Council Act 1995 (Statute No 041, Commenced: 1 November 1995) to administer the Chatham Islands and the adjoining sea, known as the "Chatham Islands Territory".

[3] The Chatham Islands Council comprises a mayor and eight councillors, all elected at-large by a first-past-the-post system.