Tynset is a municipality in Innlandet county, Norway. It is located in the traditional district of Østerdalen. The administrative centre of the municipality is the town of Tynset. Some of the notable villages in Tynset include Fådalen, Fåset, Kvikne, Telneset, Tylldalen, and Yset.

The 1,880-square-kilometre (730 sq mi) municipality is the 43rd largest by area out of the 357 municipalities in Norway. Tynset Municipality is the 168th most populous municipality in Norway with a population of 5,722. The municipality's population density is 3 inhabitants per square kilometre (7.8/sq mi) and its population has increased by 2.6% over the previous 10-year period.

The parish of Tønsæt was established as a municipality on 1 January 1838 (see formannskapsdistrikt law). In 1864, the southern part of the municipality (population: 3,216) was separated to form the new Lille-Elvdal Municipality. This left Tynset Municipality with 2,975 residents. During the 1960s, there were many municipal mergers across Norway due to the work of the Schei Committee. On 1 January 1966, the neighboring Kvikne Municipality was dissolved and on that date the southern part of Kvikne Municipality (population: 664) was merged into Tynset Municipality (the northern part of Kvikne became part of Rennebu Municipality in Sør-Trøndelag county). On 1 January 1970, the Garlia farm (population: 5) was transferred from Tynset Municipality to the neighboring Rennebu Municipality (which also meant switching from Hedmark county to Sør-Trøndelag county). On 1 January 1984, the unpopulated Spekedalen area was transferred from Tynset Municipality to the neighboring Rendalen Municipality.

Historically, the municipality was part of Hedmark county. On 1 January 2020, the municipality became a part of the newly-formed Innlandet county (after Hedmark and Oppland counties were merged).

The municipality (originally the parish) is named after the old Tynset farm (Old Norse: Tunnusetr) since the first Tynset Church was built there. The first element is the genitive case of the river name Tunna (now spelled Tonna). The meaning of the river name is not known. The last element is setr which means "mountain pasture" or "farm". Historically, the name of the municipality was spelled Tønset (pronounced Teunset with the "eu" diphthong equivalent to that in the French word bleu). On 3 November 1917, a royal resolution changed the spelling of the name of the municipality to Tynset.

The coat of arms was granted on 18 October 1985. The official blazon is "Azure, a moose head issuant argent" (Norwegian: I blått et oppvoksende sølv elghode). This means the arms have a blue field (background) and the charge is a stylized moose head extending up from the base of the escutcheon. The moose head 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 to symbolize the abundance of moose in the area. The arms were designed by Nils Aas. The municipal flag has the same design as the coat of arms.

The Church of Norway has four parishes (sokn) within Tynset Municipality. It is part of the Nord-Østerdal prosti (deanery) in the Diocese of Hamar.

Tynset is the urban centre for the northern Østerdalen part of Innlandet county in the central area of mainland Norway. Tynset Municipality lies in the upper quadrant of Norway's longest valley, Østerdalen, at an elevation of approximately 480 metres (1,574.8 ft) above sea level. To the northeast lies Tolga Municipality, to the south are Rendalen Municipality and Alvdal Municipality, to the west is Folldal Municipality, to the north are Rennebu Municipality and Midtre Gauldal Municipality (both in Trøndelag county), and to the west by Oppdal Municipality (also in Trøndelag county).