Enontekiö (Finnish: [ˈenontekiø]; Northern Sami: Eanodat [ˈe̯anoðah(t)]; Swedish: Enontekis; Inari Sami: Iänudâh; Skolt Sami: Jeänõk) is a municipality in the Finnish part of Lapland with approximately 1,800 inhabitants. It is situated in the outermost northwest of the country and occupies a large and very sparsely populated area of about 8,400 square kilometres (3,200 sq mi) between the Swedish and Norwegian border. Finland's highest point, the Halti fell, with a height of 1,324 metres (4,344 ft) above the mean sea level, is situated in the north of Enontekiö. The municipality shares borders with regions of Sweden and Norway that encompass the Scandinavian Mountains. The administrative centre of Enontekiö is the village of Hetta. About one fifth of the community's population are Sami people. Enontekiö's main industries are tourism and reindeer husbandry.

Enontekiö is located in the region of Lapland in the outermost northwest tip of Finland. The salient between the Swedish and Norwegian borders, which is occupied by the municipality of Enontekiö, is called Käsivarsi (Finnish for "arm"), because before World War II, Finland's borders had the shape of a woman's figure (Suomi-neito) and the area looked like her raised right arm. The municipality occupies a large and sparsely populated area of 8,391.35 km² (3,239.92 sq mi) (more than three times the area of Luxembourg). Thus Enontekiö is Finland's third-largest municipality in size, after Inari and Sodankylä, and with a population density of only 0.22/km² (0.57/sq mi), it is the second-most sparsely populated municipality, after Savukoski.

Enontekiö's neighbouring municipalities are Inari in the east, Kittilä in the southeast, and Muonio in the south; on the Swedish side in the west, there is Kiruna Municipality and on the Norwegian side in the north, there are Storfjord Municipality, Gáivuotna Municipality (also known as Kåfjord), Nordreisa Municipality, and Kautokeino Municipality. Enontekiö shares a border of more than 450 kilometres (280 mi) with the two adjacent nations. The border to Sweden is formed by the river Muonionjoki and its tributary, Könkämäeno.

The main village of Enontekiö is the settlement of Hetta in the south, with approx. 530 inhabitants. There is no village with the name of Enontekiö, but Hetta is often called the municipality's name. Other important places are the village of Kilpisjärvi, which is located near the border triangle of Finland-Sweden-Norway, as well as Karesuvanto and Palojoensuu, both of which are located at the Muonionjoki at the Swedish border. Enontekiö's villages are concentrated in the southern area and along the banks of the rivers Könkämäeno and Muonionjoki in the west of the municipality. Often, there is a corresponding village on the Swedish side of the river, bearing the same name (or the Swedish form of the name), e.g. Karesuvanto/Karesuando. In contrast, the part of the Käsivarsi Mountains away from the rivers is almost completely uninhabited.

The following villages belong to Enontekiö (Sami name, if available, in parentheses):

In its northern region, Enontekiö shares borders with areas of Sweden and Norway in which segments of the Scandinavian Mountains are located. Through that and through its location in the far north of Finland, it is geologically and scenically very different from the rest of the country. Halti, the highest mountain of Finland with a height of 1,324 m, is located in Enontekiö, together with all 21 other mountains higher than 1,000 m (3,281 ft) in the country. Besides Haltitunturi, probably the best known and scenically most distinctive mountain is the Saana with a height of 1,029 metres (3,376 ft), which rises above the village of Kilpisjärvi. The southern part of the municipality is less mountainous, but some single fjells (tunturi, which means hills towering above the timber line) rise above the otherwise rather flat surrounding area. Below, a part of the Pallastunturi–Ounastunturi-massif extends into Enontekiö's territory.

A little more than 5% of the municipality's area consists of water. Several large rivers originate in Enontekiö: The Muonionjoki, Ounasjoki, Ivalojoki, and one of the headstreams of the Tenojoki have their sources in the municipality. Enontekiö owes its name to them: Eno is an old Finnish word for "major river" cognate with the Northern Sámi word Eatnu or "large river, largest river (in a specific region)" and tekiö is derived from the Northern Sámi derivational suffix -dat which forms abstract nouns. All of the 825 lakes in the area are rather small. The largest lakes are the Pöyrisjärvi, the Kilpisjärvi near the village with the same name, and the Ounasjärvi near Hetta.

The vegetation of Enontekiö is very meagre, due to the extreme northern latitude. The northern border of the natural geographic range of the spruce approx. matches the southern border of the municipality; the range of the pine ends only 20 km (12 mi) north of Hetta, too. North of that, only birches grow. The timber line is approximately 600 m (2,000 ft); above that, a tundra-like vegetation predominates. Heaths extends above timber line.