Sunndal^ⓘ is a municipality in the Nordmøre region located in the northeast part of Møre og Romsdal county, Norway. The administrative center of the municipality is the village of Sunndalsøra. Other villages include Gjøra, Grøa, Holssanden, Jordalsgrenda, Romfo, Ålvund, Ålvundeidet, and Øksendal. With an area of 1,713 square kilometres (661 sq mi), it is the largest municipality in Møre og Romsdal county. The important occupations in Sunndal include industry (with Hydro Aluminium Sunndal as the biggest employer), public services, retail, and farming.

The 1,713-square-kilometre (661 sq mi) municipality is the 47th largest by area out of the 357 municipalities in Norway and it is the largest by area in Møre og Romsdal county. Sunndal Municipality is the 141st most populous municipality in Norway with a population of 7,227. The municipality's population density is 4.2 inhabitants per square kilometre (11/sq mi) and its population has increased by 0.8% over the previous 10-year period.

The parish of Sunndal was established as a municipality on 1 January 1838 (see formannskapsdistrikt law). In 1854, the northern part of the municipality (population: 1,291) was separated to form the new Øksendal Municipality. This left 2,188 residents in Sunndal Municipality.

During the 1960s, there were many municipal mergers across Norway due to the work of the Schei Committee. On 1 January 1960, the neighboring Ålvundeid Municipality (population: 513) and Øksendal Municipality (population: 497) were merged with Sunndal Municipality (population: 5,851) to form a new, larger Sunndal Municipality. Both Ålvundeid Municipality and Øksendal Municipality were historically part of the municipality before 1854. Then, on 1 January 1965, the Ålvund-Ålvundfjorden area of the neighboring Stangvik Municipality (population: 508) was transferred into Sunndal Municipality.

The municipality (originally the parish) is named after the Sunndalen valley (Old Norse: Sunndalr). The first element is sunnr or suðr which mean "southern". The last element is dalr which means "valley" or "dale". Historically, the name was spelled Sunddalen (or Sunndalen). In 1870, the spelling was changed to Sundalen. On 3 November 1917, a royal resolution changed the spelling of the name of the municipality to Sunndal, adding an "n" and removing the definite form ending -en.

The coat of arms was granted on 12 April 1983. The official blazon is "Vert, a wormwood plant argent" (Norwegian: I grønt en sølv malurt). This means the arms have a green field (background) and the charge is a Norwegian wormwood (Artemisia norvegica) plant. The plant has a tincture of argent which means it is commonly colored white, but if it is made out of metal, then silver is used. The design was chosen in a competition for the municipal arms. This design was chosen since this plant species is only found in a few places in the world. It has its main European distribution in Sunndal Municipality and neighboring Oppdal Municipality in the Dovrefjell-Sunndalsfjella National Park and in Trollheimen landscape protection area. Small populations are also found in Ryfylke, Scotland, and the Ural Mountains, with another subspecies in the mountains of Northern America. This plant can be found in abundance in many places in the mountains of Sunndal well above tree line. The arms were designed by Svein Thuen Rasmussen. The municipal flag has the same design as the coat of arms.

The Church of Norway has four parishes (sokn) within Sunndal Municipality. It is part of the Indre Nordmøre prosti (deanery) in the Diocese of Møre.

Sunndal is bordered on the west by Molde Municipality and Tingvoll Municipality, on the north by Surnadal Municipality, on the east by Oppdal Municipality (in Trøndelag county) and on the south by Lesja Municipality (in Innlandet county).