After a short stretch in the town of Blackstone and Worcester County, Route 126 enters the town of Bellingham and Norfolk County, heading north.

In the north of the town, the route turns east on Hartford Avenue, crossing I-495 at Exit 18.

The road bears to the right, passing Gleason Pond before crossing over Route 9 with exit ramps between the two.

Route 126 continues northward, crossing the Massachusetts Turnpike (I-90) without junction.

As it passes Lake Cochituate, Route 126 enters the town of Wayland.