Island Bay was a former New Zealand electorate, centred on Island Bay in the southern suburbs of Wellington. The electorate was formed in 1946 and dissolved in 1996.

The 1941 New Zealand 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 Island Bay.^[1]

The electorate was held by five MPs from the Labour Party for the whole of its existence from 1946 to 1996.^[2] Robert McKeen was the first representative; he had since the 1922 election represented the Wellington South electorate.^[3] McKeen was the Speaker of the House of Representatives from 1947 to 1950.^[4] He retired from Parliament in 1954.^[3]

McKeen was succeeded by Arnold Nordmeyer in the 1954 election.^[5] Nordmeyer was Minister of Finance in the Second Labour Government from 1957 to 1960,^[6] and is remembered for the black budget which contributed to Labour's defeat in 1960.^[7] Nordmeyer had moved to the Island Bay electorate when the Brooklyn electorate was abolished.^[5]

Gerald O'Brien was deselected by Labour for the electorate in 1978, and ran against the new Labour candidate Frank O'Flynn. O'Flynn was Minister of Defence in the Fourth Labour Government from 1984 to 1987.