State Route 186 (SR 186) is a north–south state highway in the northwestern part of the U.S. state of Ohio. Traveling through mostly rural areas, State Route 186 has its southern terminus at a T-intersection with the U.S. Route 224/State Route 15 concurrency nearly 3.5 miles (5.6 km) south-southeast of McComb. Following a 1-mile (1.6 km) long concurrency with State Route 235 into McComb, State Route 186 arrives at its northern terminus at its junction with State Route 613.