Magliaso is a municipality in the district of Lugano in the canton of Ticino in Switzerland.

Magliaso is first mentioned in 769 as de Maliacis. In 854 it was mentioned as de vico Maliaci.

During the Lombards era the monastery of San Pietro in Ciel d'Oro in Pavia possessed a farm in Magliaso. The origin of the old church of S. Quirico (mentioned in 1033) and the San Giorgio Castle is not known. It was the home for nearly two decades (1098–1117) for the schismatic bishop of Como, Landolfo Carcano, who was appointed by Emperor Henry IV against Pope Gregory VII's bishop. The castle was besieged and conquered in 1117 by Como and the fate of Landolfo is uncertain (possibly deported or murdered). This caused the ten-year war between Como and Milan. The romanesque fresco on the south tower dates from around the same time and is one of the few secular romanesque works in Switzerland. In the 13th century the castle passed into the possession of a branch of the Rusca family of Como. Carlo Corrado Beroldingen, Chancellor of the bailiwick of Lugano, acquired the sovereign rights over the village in 1668. He had the parish church built and replaced the decaying ruins of the castle with an ornate palace.

There used to be many isolated farms and mills along the irrigation canal, which is typical for the pre-industrial economy. The municipality experienced a strong migration into Lombardy, South America and up through the 2nd World War into Central Switzerland. The always meager possessions of Vicinanza were sold in 1863. At the beginning of the 21st century, large swathes of the valley and along the lake were covered with new, primarily residential, developments. While the services sector is the major industry in Magliaso, the tourist infrastructure has remained modest. The landscape is dominated by the lake, and in an area at the foot of the mountain, a golf course was built.

Magliaso has an area, as of 1997^[update], of 1.09 square kilometers (0.42 sq mi). Of this area, 0.73 km² (0.28 sq mi) or 67.0% is used for agricultural purposes, while 0.1 km² (0.039 sq mi) or 9.2% is forested. Of the rest of the land, 0.77 km² (0.30 sq mi) or 70.6% is settled (buildings or roads), 0.03 km² (7.4 acres) or 2.8% is either rivers or lakes.

Of the built up area, housing and buildings made up 48.6% and transportation infrastructure made up 11.9%. while parks, green belts and sports fields made up 9.2%. Out of the forested land, 4.6% of the total land area is heavily forested and 4.6% is covered with orchards or small clusters of trees. Of the agricultural land, 12.8% is used for growing crops, while 5.5% is used for orchards or vine crops and 48.6% is used for alpine pastures. Of the water in the municipality, 0.9% is in lakes and 1.8% is in rivers and streams.

The municipality is located in the Lugano district, north of the Magliasina delta. It consists of the villages of Magliaso, below the church and castle, and Castellaccio, on the lake shore.

The blazon of the municipal coat of arms is Quartered or in first and fourth two mullets of the same on an orb azure with a cross sable and in second and third also or a lion rampant sable scarfed azure.