Bolsøy is a former municipality in Møre og Romsdal county, Norway. The 271-square-kilometre (105 sq mi) municipality existed from 1838 until its dissolution in 1964. The area is now part of Molde Municipality in the traditional district of Romsdal. The administrative centre was Bolsøy on the island of Bolsøya where the Bolsøy Church is located.

Prior to its dissolution in 1964, the 270.7-square-kilometre (104.5 sq mi) municipality was the 304th largest by area out of the 689 municipalities in Norway. Bolsøy Municipality was the 97th most populous municipality in Norway with a population of about 7,888. The municipality's population density was 29.1 inhabitants per square kilometre (75/sq mi) and its population had increased by 30.9% over the previous 10-year period.

The parish of Bolsøy was established as a municipality on 1 January 1838 (see formannskapsdistrikt law). According to the 1835 census, Bolsøy had a population of 2,391. On 1 January 1877, the Sotnakken farm (population: 19) was transferred to Bolsøy Municipality from Nesset Municipality. In 1915, a part of Bolsøy Municipality with 183 inhabitants was transferred to the growing town of Molde. Again in 1952, another part of Bolsøy Municipality (population: 1,913) was transferred to the town of Molde.

During the 1960s, there were many municipal mergers across Norway due to the work of the Schei Committee. On 1 January 1964, the following areas were merged to form a new, larger Molde Municipality:

The municipality (originally the parish) is named after the island of Bolsøya (Old Norse: Bylingsøy) since the first Bolsøy Church was built there. The first element comes from the old name for the island. The island's name is uncertain, but it may come from the word boli which means "bull". The last element is øy which means "island". Historically, the name of the municipality was spelled Bolsø. On 3 November 1917, a royal resolution changed the spelling of the name of the municipality to Bolsøy.

The Church of Norway had three parishes (sokn) within Bolsøy Municipality. At the time of the municipal dissolution, it was part of the Bolsøy prestegjeld and the Ytre Romsdal prosti (deanery) in the Diocese of Nidaros.

The municipality was centered around the Moldefjorden and Fannefjorden, surrounding the town of Molde. Fræna Municipality and Øre Municipality were to the north, Nesset Municipality was to the southeast, Veøy Municipality was to the south, and Nord-Aukra Municipality was to the west. The highest point in the municipality was the 1,127.7-metre (3,700 ft) tall mountain Skåla, located about 10 kilometres (6.2 mi) to the northeast of the village of Nesjestranda.

While it existed, Bolsøy Municipality was responsible for primary education (through 10th grade), outpatient health services, senior citizen services, welfare and other social services, zoning, economic development, and municipal roads and utilities. The municipality was governed by a municipal council of directly elected representatives. The mayor was indirectly elected by a vote of the municipal council. The municipality was under the jurisdiction of the Frostating Court of Appeal.