Route 105 is a south–north state highway in southeastern Massachusetts.

Route 105 begins at U.S. Route 6 in Marion. The highway crosses over I-195 less than a mile into its journey. The highway winds in a westerly direction through Rochester. When the highway enters Long Plain village in Acushnet, the only town in Bristol County on the route, Route 105 turns in a northerly direction. The highway returns into Rochester and enters Lakeville between Little Quittacas and Great Quittacas Ponds. Route 18 joins Route 105 for a 2.7-mile (4.3 km) concurrency, running along the western shore of Assawompset Pond. Route 105 then shoots off in a northeasterly direction into Middleborough through the town’s center and, after its intersection with U.S. Route 44, turns in a northerly direction through East Middleborough, going past Oak Point along the way. The highway ends at Route 106 in Halifax west of the town's center.

When U.S. Route 44 bypassed Middleborough in the early 1960s, Route 105 took over the former Route 44 as far as Thompson Street, and eventually was extended north along Thompson Street to Halifax.