Route 225 and Route 119 continue southeast along Boston Road to their split in the southeast corner of Groton, where Route 119 continues along Boston Road while Route 225 turns east onto Forge Village Road. The highway enters the town of Westford along Prescott Street and has a grade crossing of a railroad, where the highway continues on Pleasant Street. Southeast of the town center, Route 225 continues along Concord Road. The highway crosses over Interstate 495 (I-495) with no access shortly before its western junction with Route 110 (Littleton Road). The two routes briefly run concurrently on four-lane Littleton Road before Route 225 diverges onto Concord Road, which becomes Carlisle Road midway between Route 110 and Route 27 (Acton Road). East of Route 27, Route 225 enters Carlisle, where the highway follows Westford Street and then Bedford Road east of the town center.