Brusio (Lombard: Brus; Romansh: Brüsch) is a municipality in the Bernina Region in the canton of Grisons in Switzerland.

In the 13th century, the entire Val Poschiavo became part of the fief of the Bishop of Chur.

During the 14th century, Brusio was part of the practically (although not officially) independent municipality of Poschiavo.

During the conquest of the Valtellina valley by the Three Leagues, the hamlets of Campocologno (1518) and Zalende (1526) were founded.

In 1863 the previously Italian side valley of Saiento and the hamlet of Cavajone joined Brusio and became Swiss.

Of the rest of the land, 2.3% is settled (buildings or roads) and the remainder (27%) is non-productive (rivers, glaciers or mountains).

Besides the village of Brusio itself, it consists of the hamlets of Campocologno, Zalende, Campascio, Piazzo and parts of Miralago as well as the small settlements of Viano and Cavaione high in the mountains.

[4] From the 2000 census[update], 1,052 or 87.5% are Roman Catholic, while 91 or 7.6% belonged to the Swiss Reformed Church.

All three are located on the Bernina line, with regular service to St. Moritz and Tirano.