Horowhenua District is a territorial authority district on the west coast of the North Island of New Zealand, administered by Horowhenua District Council. Located north of Wellington and Kāpiti, it stretches from slightly north of the town of Ōtaki in the south to just south of Himatangi in the north, and from the coast to the top of the Tararua Range. It is in the Manawatū-Whanganui local government region. The name Horowhenua is Māori for landslide.

The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but less populous South Island by Cook Strait. With an area of 113,729 km2 (43,911 sq mi), it is the world's 14th-largest island, constituting 43% of New Zealand's land area. It has a population of 3,997,300, which is 77% of New Zealand's residents, making it the most populous island in Polynesia and the 28th-most-populous island in the world.