The Tilton River is a tributary of the Cowlitz River, in the state of Washington. Named for territorial surveyor James Tilton, it flows for about 29 miles entirely within Lewis County.

The Tilton River originates in the Cascade Range just north of Mount St. Helens and southwest of Mount Rainier. It flows south and west, joining the Cowlitz River in Lake Mayfield, near Mossyrock. 

Tilton River flows through the town of Morton and past Ike Kinswa State Park. Known for fishing, swimming and white water rafting during some times of the year.