Ulstein is a municipality in Møre og Romsdal county, Norway. It is part of the Sunnmøre region. The commercial and administrative centre of Ulstein is Ulsteinvik, population 5,251 (2009). The municipality occupies the western half of the island of Hareidlandet, as well as about 30 or more smaller islands, four of which are populated. Ulstein is connected to the mainland of Norway by the Eiksund Bridge (to the island of Eika) and then the Eiksund Tunnel to Ørsta.
The municipality of Ulstein (originally Ulfsteen) was established as a municipality on 1 January 1838 (see formannskapsdistrikt). The area southeast of the Vartdalsfjorden was separated from Ulstein on 1 January 1895 to become the new municipality of Vartdalsstranden. This left Ulstein with 2,996 residents. Then on 1 January 1917, the eastern half of the island of Hareidlandet was separated from Ulstein to form the new municipality of Hareid. This left 2,336 residents in Ulstein. On 1 January 1964, the island of Eika and the village of Eiksund (population: 222) were transferred from Herøy to Ulstein.