Known as Seneca Road, the highway runs 2.81 miles (4.52 km) from MD 190 near Seneca east to MD 28 in Darnestown in western Montgomery County.

MD 112 was constructed in Darnestown in the early 1920s and extended to Seneca in the late 1920s.

That highway heads southeast toward Potomac; county-maintained River Road heads west through the hamlet of Seneca near the mouth of Seneca Creek and the Seneca Historic District.

MD 112 heads east and then northeast as a two-lane undivided road.

The highway transitions from rural to suburban surroundings before reaching its eastern terminus at MD 28 (Darnestown Road) in the village of Darnestown.