Richwood is a village in Union County, Ohio, United States. The population was 2,156 at the 2000 census.
The town of Richwood was laid out in 1832, by Philip Plummer. In 1834, road work was completed, and all the roads going into the town were gravelled. As of 1877, the town contained one newspaper, two banks, three churches, one brick school-house, and several stores and factories.
Richwood is located at 40°25′37″N 83°17′51″W / 40.42694°N 83.2975°W / 40.42694; -83.2975 (40.426927, -83.297404).