Through an amendment in the Electoral Act in 1965, the number of electorates in the South Island was fixed at 25, an increase of one since the 1962 electoral redistribution.
This current Waitaki electorate is the successor to parts of the old Otago electorate, with parts of central Otago moving into Clutha-Southland, and the boundary extended far up the South Canterbury coast, to just outside Timaru.