State Route 84 is an east–west state highway in the northeastern portion of the U.S. state of Ohio. Its western terminus is along U.S. Route 6 at U.S. Route 20 in Euclid, and its eastern terminus is at the Pennsylvania state line about 10 miles (16 km) south-southeast of Conneaut; Pennsylvania Route 226 continues eastward.

A portion of State Route 84 runs along the historic Johnnycake Ridge Road.