Carlsfjella is a mountain ridge in Oscar II Land at Spitsbergen, Svalbard. The ridge has a length of 14 kilometers, is located between St. Jonsfjorden and Løvenskioldfonna, and includes Valentinryggen, Patronen, Knausen and Haraldfjellet. The ridge is named after land owner Carl Otto Løvenskiold.
Coordinates: 78°38′00″N 13°01′52″E / 78.6334°N 13.0310°E