- The Waitaki district, in the Canterbury and Otago regions of New Zealand, straddles the traditional border between the two regions, the Waitaki River.
- It has a land area of 7,151.94 km² (2,761.38 sq mi), divided 59.28% to Canterbury Region and 40.72% to Otago Region.
- It is the only district in the South Island that is divided between two regions. A major reason for this split was the governance of the Waitaki River which forms a political boundary between Canterbury and Otago. With major hydro schemes on this river, it was decided to place the entire catchment in one administrative region, thus forming the split. Some people who fall into the Canterbury Region of Waitaki District still regard themselves as part of Otago, and attempts have been made in the past to change the boundary.
- The district, which is agricultural by nature, comprises the wide alluvial fan of the river, and runs inland along the banks of the river, this forming a roughly triangular region. Oamaru, on the Otago side of the river, is the largest town in the district, with a population of 22,308 (as at 2018).
- The Waitaki District is made up of the former Waitaki County, Waihemo County and Oamaru Borough, which were merged in 1989. It is governed by the Waitaki District Council.