Although the headwaters of the Chagrin River are near Aurora
, the main river starts coming together close to Chagrin Falls
near the Cuyahoga County
line about 15 miles southeast of Cleveland
in northeastern Ohio.
The river forks with the main branch heading north and a smaller branch heading to the northeast to flow through Chardon before returning to a northerly tack. The two branchs merge in Willoughby before emptying into Lake Erie at Mentor.