State Route 99 (SR 99) is a north–south state highway in the north-central portion of the U.S. state of Ohio. The highway's southern terminus is in the southern end of Willard at a T-intersection with U.S. Route 224 (US 224). Its northern terminus is at its junction with SR 4 about 6 miles (9.7 km) southwest of the city limits of Sandusky.