Route 101 is a 22.55-mile-long (36.29 km) north–south state highway in Massachusetts.

The route heads eastward, winding between two wildlife management areas and south of Queen Lake as it passes through Phillipston.

From Templeton, Route 101 enters the city of Gardner, acting as one of the main streets through town.

In Ashburnham, Route 101 heads into the center of town, sharing a short concurrency along Route 12 before turning northward, passing by Winnekeag Lake and west of Ward Pond before ending at Route 119, three miles south of the New Hampshire state line and 300 yards east of the Ashby town line.

The entire route is in Worcester County.