Rollag is a municipality located in Buskerud county, Norway. It is situated within the traditional region of Numedal and serves as a rural administrative area.
The village of Rollag functions as the administrative centre of the municipality, though Veggli is identified as its most populated area. The municipality is bordered by Nore og Uvdal to the north, Sigdal to the east, Flesberg to the south, and Tinn in Telemark to the west.