Molinis is a former municipality in the district of Plessur in the canton of Graubünden in Switzerland. On 1 January 2013 the former municipalities of Molinis, Calfreisen, Castiel, Langwies, Lüen, Peist and St. Peter-Pagig merged into the municipality of Arosa.
Molinis is first mentioned in 1335 as Mulina. Formerly, in Romansh, it was known as Molinas.
Before the merger, Molinis had a total area of 13.2 km2 (5.1 sq mi). Of this area, 26.7% is used for agricultural purposes, while 60.8% is forested. Of the rest of the land, 1.4% is settled (buildings or roads) and the remainder (11%) is non-productive (rivers, glaciers or mountains).
The former municipality is located in the Schanfigg sub-district of the Plessur district, on the Schanfigg valley floor. It consists of the haufendorf village (an irregular, unplanned and quite closely packed village, built around a central square) of Molinis.
Nearby is the Sankt Peter-Molinis railway station, on the Chur-Arosa railway line, which also serves Sankt Peter.