Rio Dell is an unincorporated community in Sonoma County, California, United States. It is located on the south bank of the Russian River about 2 mi (3 km) north of Forestville. It adjoins Steelhead Beach Regional Park, which provides a beach, picnic area, and a small craft launching area.
The main road is River Road, which passes northwest to southeast through Rio Dell. The next community to the northwest is Hollydale. The next community to the southeast is Mirabel Park.