Known as Mount Carmel Road, the state highway runs 8.50 miles (13.68 km) from Gunpowder Road near Hampstead east to MD 45 at Hereford in northern Baltimore County.

MD 137 begins at a three-way intersection with Gunpowder Road, which heads east toward Prettyboy Reservoir, and a county-maintained continuation of Mount Carmel Road west toward Hampstead.

The state highway continues east through farmland along the drainage divide between Gunpowder Falls to the north and its tributary Western Run to the south and passes its namesake church, now named Mount Carmel United Methodist Church.

MD 137 meets Interstate 83 (I-83, Harrisburg Expressway) at a diamond interchange with ramps staggered into four intersections.

A park and ride lot is located within the northwest quadrant of this interchange.