Lake of Gruyère (French: Lac de la Gruyère; German: Lac de la Gruyère or Greyerzersee) is an artificial lake in the La Gruyère region of the Canton of Fribourg , Switzerland .

The reservoir was formed between the cities of Bulle and Fribourg, by building the Rossens Dam on the Sarine river in 1948. The arch dam has a height of 83 m and a crest length of 320 m. The reservoir filled in about four months after completion. The dam is operated by the Groupe E SA.

The remains of the castle of Pont (or Pont-en-Ogoz ) and a chapel are located on the Ile d'Ogoz, one of the five islets in the lake.

The "Viaduc du Lac de Gruyère" of the A12 motorway was built in the 1970s.