State Route 29 (SR 29) is an east–west state highway in the west-central portion of the U.S. state of Ohio. Its western terminus is at the Indiana state line near Celina, where State Road 67 continues west. It continues east to St. Marys where it junctions with U.S. Route 33. In that town, it also crosses State Route 66, State Route 116, and State Route 703, which was its former alignment before a divided highway was built.