State Route 177 (SR 177) is a north–south state highway located in the southwest corner of the U.S. state of Ohio. The southern terminus of State Route 177 is at the signalized junction of State Route 4 and State Route 129 in Hamilton, after State Route 177 runs concurrently with State Route 129 for its southernmost 1.59 miles (2.56 km). The northern terminus of State Route 177 is at the Indiana State Line approximately 3.75 miles (6.04 km) northwest of the unincorporated community of Fairhaven. From this point, State Route 177 continues into Indiana as Indiana State Road 227.