Waitakere was a parliamentary electorate, returning one Member of Parliament to the House of Representatives of New Zealand. The electorate was first formed for the 1946 election and existed until 2014, with breaks from 1969 to 1978 and from 1987 to 1993. The last MP for Waitakere was Paula Bennett of the National Party, who had held this position since the 2008 election.
The 1941 census had been postponed due to World War II, so the 1946 electoral redistribution had to take ten years of population growth and movements into account. The North Island gained a further two electorates from the South Island due to faster population growth. The abolition of the country quota through the Electoral Amendment Act, 1945 reduced the number and increased the size of rural electorates. None of the existing electorates remained unchanged, 27 electorates were abolished, eight former electorates were re-established, and 19 electorates were created for the first time, including Waitakere.
Waitakere was based around the western suburbs of Auckland. Given the nature of population growth in greater Auckland, and the addition of three new seats in Auckland, the boundaries of Waitakere moved around at every electoral redistribution; in 1999, they were moved northwards as far as Helensville before being pulled back south three years later. In its last boundaries before abolition, the electorate included the Waitakere City suburbs of Henderson, Ranui and Swanson before heading west over the Waitakere Ranges to Piha.