State Route 27 (abbreviated SR 27) is part of Maine's system of numbered state highways, running 154.1 miles (248.0 km) from the village of Newagen in Southport at SR 238 to the Coburn Gore–Woburn Border Crossing, where it continues into Quebec as Route 161.

SR 27 passes through the major cities, towns, and villages of Boothbay Harbor, Wiscasset, Gardiner, Augusta, the Belgrade Lakes Region, Farmington, Kingfield, and Eustis.

Continuing north, SR 27 leaves US 201 and turns northwest toward Belgrade.

It then joins US 2, enters the town of New Sharon, and intersects SR 134.

The two routes enter Carrabassett Valley, where they pass Sugarloaf Mountain.