Lake Carmi is a small and relatively shallow lake located in the town of Franklin, in the northwest corner of Vermont, United States. It is the fourth largest lake, and has a 1,375 acres (5.56 km2) surface area, an average depth of 20 ft (6.1 m) and a maximum depth of 33 ft (10 m).

The lake drains northwards into the Pike River in Quebec. Lake Carmi was once much larger. In the thousands of years since the last ice age, the southern end of the original lake has silted in, creating wetland forests and the third largest peat bog in Vermont. Vermont Route 120 runs along the northern shoreline.