Ollon is a municipality in the district of Aigle in the canton of Vaud in Switzerland, sited in the foothills of the mountains to the south-east of the Lake of Geneva. The old German language name Olun is no longer used.

Ollon is first mentioned in 1018 as Aulonum though there is some debate about whether this refers to another settlement. In 1025-1032 it was mentioned as Olonum.

The village of Saint-Triphon is situated on three hills overlooking the Rhone valley. It was first mentioned in 1332 as Triphonis Sancti. Archeological finds include items from the Middle Neolithic to the Roman era, including an Early Bronze Age necropolis and a Late Bronze Age smelter for copper processing.

On the hill Le Lessus stands a 18 m (59 ft) high square tower, probably from the 13th century. The tower was partially destroyed in 1476. Foundations indicate that the tower was reached by a walkway. Nearby, the remains of a romanesque chapel from the 12th century is still visible. In 1232 the Counts of Savoy granted the castle to Guy de Saillon. The fief was dismembered in the 14th century and reunited in the 16th century under the Rovéréa family. Between 1476 and 1798 it was one of the twelve Zenden des Mandements Ollon in the government of Aigle. The village was ruled by a Bernese mayor. Since the Middle Ages, black marble has been mined in the village.

Ollon has an area of 59.54 square kilometers (22.99 sq mi). Of this area, 23.86 km² (9.21 sq mi) or 40.1% is used for agricultural purposes, while 27.11 km² (10.47 sq mi) or 45.5% is forested. Of the rest of the land, 6.3 km² (2.4 sq mi) or 10.6% is settled (buildings or roads), 0.55 km² (0.21 sq mi) or 0.9% is either rivers or lakes and 1.68 km² (0.65 sq mi) or 2.8% is unproductive land.

Of the built up area, housing and buildings made up 5.6% and transportation infrastructure made up 3.1%. Out of the forested land, 38.9% of the total land area is heavily forested and 4.8% is covered with orchards or small clusters of trees. Of the agricultural land, 11.1% is used for growing crops and 8.5% is pastures, while 2.9% is used for orchards or vine crops and 17.7% is used for alpine pastures. Of the water in the municipality, 0.3% is in lakes and 0.6% is in rivers and streams.

The municipality is located in the Aigle district. The area covered by Ollon borders the Rhône on the southwest side, and rises up the mountainside as far as Chamossaire. Ollon includes 123 hectares (300 acres) of vineyards. It is one of the largest municipalities in the canton. It consists of the village of Ollon and 23 other villages and hamlets (including; Antagnes, Arveyes, Chesières, Huémoz, Panex, Saint-Triphon, Villars-sur-Ollon) as well as scattered summer grazing camps (Bretaye, Les Closalets, La Barboleusaz).

The blazon of the municipal coat of arms is Quartered Vert and Gules, overall a Cross couped Argent.