Auckland City refers to two former territorial authorities based around Auckland, New Zealand. The first Auckland City, also known as the City of Auckland, existed from 1871 until the 1989 local government reforms when it was replaced with an eponymous authority that covered the whole Auckland isthmus, which lasted until 2010 when it was replaced with the region wide Auckland Council. The post-1989 authority was governed by the Auckland City Council and by the larger Auckland Regional Council.

The territory of Auckland grew from just covering the central business district to encompass suburbs such as Ponsonby and Parnell, although several suburbs remained independent boroughs until the 1989 local government reforms, when the nascent Auckland City was constituted as covering the entire isthmus and islands within the Hauraki Gulf such as Waiheke.

Auckland was constituted a city On 24 April 1871 under The Municipal Corporations Act, 1867 by Parliament. Previously Auckland was an independent borough.

The boundaries of Auckland were Stanley Street, Symonds Street, Karangahape Road, Ponsonby Road, and Franklin Road. It was initially 623 acres (252 ha) in size. In 1882 it more than doubled in size by amalgamating the neighbouring highway districts of Ponsonby, Karangahape, and Grafton. The boundaries remained static until a period of multiple amalgamations between 1913 and 1921 resulted in an increase to 7,844 acres (3,174 ha), an almost five-fold increase. These amalgamations were: 15 February 1913, Parnell Borough; 1 April 1913, Arch Hill Road District; 1 July 1914, Grey Lynn Borough; 1 March 1915, Remuera Road District; 1 October 1915, Eden Terrace Road District; 1 February 1917, Epsom Road District; 1 April 1918 188 acres (76 ha) from West Tamaki Road District, to incorporate lake St John; 1 March 1921; 1 March 1921, Point Chevalier Road District. Further amalgamations included Avondale Borough on 1 September 1927, West Tamaki and Orakei Road District on 1 April 1928. From 1928 to 1971 the city did not change boundaries except for harbour reclamations and the inclusion of the Auckland Domain and the loss of 9 acres (3.6 ha) to the Newmarket Borough. By this point the city covered 18,500 acres (7,500 ha).

By 1971 the city stretched from the Whau River in the West to the Tamaki River in the East; however, the city did not cover the entire Auckland isthmus due to the existence of several independent boroughs.

The City of Auckland used wards for electoral purposes from 1878 to 1903. Initially the city had three wards: East, West, and North, after the amalgamation of Ponsonby, Karangahape, and Grafton these districts were included as wards. In 1901 the Karangahape ward was abolished as the Municipal Corporations Act 1900 imposed a limit of 5 wards.

The mainland part of Auckland City occupied the Auckland isthmus, also known as the Tāmaki isthmus. The Waitematā Harbour, which opens to the Hauraki Gulf, separated North Shore City from the isthmus. The Manukau Harbour, which opens to the Tasman Sea, separated Manukau City from the isthmus. The distance between the two harbours is particularly narrow at each end of the isthmus. At the western end, the Whau River, an estuarial arm of the Waitematā Harbour, comes within two kilometres of the waters of the Manukau Harbour on the west coast and marks the beginning of the Northland Peninsula. A few kilometres to the southeast at Ōtāhuhu, the Tāmaki River, an arm of the Hauraki Gulf on the east coast, comes just 1200 metres from the Manukau's waters. Being part of the Auckland volcanic field, much of the isthmus is mantled with volcanic rocks and soils, and several prominent scoria cones dot the isthmus.

Many Hauraki Gulf islands were part of Auckland City. Such islands of the inner gulf included Rangitoto, Motutapu, Browns Island, Motuihe, Rakino, Ponui and Waiheke, while the outer gulf islands included Little Barrier Island, Great Barrier and the Mokohinau Islands.