Folldal is a municipality in Innlandet county, Norway. It is located in the traditional district of Østerdalen. The administrative centre of the municipality is the village of Folldal. The municipality was established in 1914 when it was separated from Alvdal Municipality.

Folldal is bordered on the north by Oppdal Municipality and Tynset Municipality; in the east by Alvdal Municipality; in the south by Stor-Elvdal Municipality, Sør-Fron Municipality, and Sel Municipality; and in the west by Dovre Municipality. Mining at the Folldal Gruver mines was the main industry for Folldal's residents from the 18th century until the last mine-related operations ceased in 1993.

The 1,277-square-kilometre (493 sq mi) municipality is the 79th largest by area out of the 357 municipalities in Norway. Folldal Municipality is the 302nd most populous municipality in Norway with a population of 1,540. The municipality's population density is 1.2 inhabitants per square kilometre (3.1/sq mi) and its population has decreased by 6.1% over the previous 10-year period.

Historically, the parish of Folldal was a part of Alvdal Municipality since 1838 (see Formannskapsdistrikt law). On 1 January 1914, the northern parish of Folldal was separated from Alvdal to become a separate municipality. Initially, Folldal Municipality had a population of 2,284. On 1 January 1970, the three western farms at Børgsungsætri (population: 11) were transferred from the neighboring Dovre Municipality (in Oppland county) to Folldal Municipality (in Hedmark county). On 28 September 1990, a small, unpopulated part of Sør-Fron Municipality (in Oppland county) was transferred to Folldal Municipality (in Hedmark county).

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 Folldal farm since the first Folldal Church was built there. The first element comes from the name of the local river Folla which has an unknown meaning (perhaps something like "the broad one"). The last element is dalr which means "valley" or "dale". Historically, the name of the municipality was spelled Folldalen. On 3 November 1917, a royal resolution changed the spelling of the name of the municipality to Folldal.

The coat of arms was granted on 21 September 1988. The official blazon is "Gules, a pickaxe Or in bend issuant from base sinister" (Norwegian: I rødt en skrått framvoksende gull hakke). This means the arms have a red field (background) and the charge is a diagonal pickaxe. The pickaxe has a tincture of Or which means it is commonly colored yellow, but if it is made out of metal, then gold is used. This design was chosen to represent the mining and agriculture industries in the municipality. The pickaxe was an important tool of miners and thus symbolizes the mining industry, which was the reason for Folldal municipality to be established in 1914. There was mining activity in the Folldal area from 1748 until 1993. The pickaxe also stands for farming as it was an essential tool in clearing the ground for farms in Folldal back when the area was first settled. The arms were designed by Sverre Morken. The municipal flag has the same design as the coat of arms.

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