The region covers all or part of ten territorial authority areas. Parts of five of these are covered by five other regions of New Zealand, the most of any region. In descending order of land area the territorial authority districts are Ruapehu, the major parts of Tararua District and Rangitikei, Manawatū, Whanganui, Horowhenua, and small parts of Stratford, Waitomo, and Taupō. The largest city is Palmerston North, with a population of 85,300 (June 2012 estimate). It is the only territorial authority in the region to be administered by a city council.
The region that is administered by the Manawatū-Whanganui Regional Council (Horizons Regional Council). Constituted by Local Government (Manawatu-Wanganui Region) Reorganisation Order 1989, Gazette 1989, p2351 Shown on SO 36010.