Mairehau (Māori pronunciation: [maiɾɛːhau]) is a suburb of Christchurch, New Zealand.

Much new development is being carried out on the northern edge of Mairehau.

The suburb was named after Rose Mairehau (Maire) Hutton (née Rhodes), daughter of Arthur Rhodes, who in turn was Mayor of Christchurch in 1901–1902 and a major local property owner.

Before the 2023 census, Mairehau had a larger boundary, covering 3.61 km2 (1.39 sq mi).

The percentage of people born overseas was 20.0, compared with 27.1% nationally.

Although some people chose not to answer the census's question about religious affiliation, 51.4% had no religion, 38.0% were Christian, 0.3% had Māori religious beliefs, 0.9% were Hindu, 1.0% were Muslim, 0.5% were Buddhist and 2.1% had other religions.