The Little Wabash River is a 240-mile-long (390 km)^[2][3] tributary of the Wabash River in east-central and southeastern Illinois in the United States. Via the Wabash and Ohio rivers, it is part of the watershed of the Mississippi River. It is the third largest tributary after the White River and the Embarras River.

Note: The Little River of northeastern Indiana is also sometimes known as the Little Wabash River.

The Little Wabash rises in Coles County near Mattoon and flows generally southwardly through Shelby, Effingham, Clay, Richland, Wayne, Edwards and White counties, past the towns of Louisville, Golden Gate, Carmi and New Haven. It enters the Wabash River on the common boundary of White and Gallatin counties, about 4 miles (6 km) southeast of New Haven.

In its upper course in Shelby County, the river is dammed to form Lake Mattoon and collects the short West Branch Little Wabash River, which flows for its entire length in Shelby County. Other tributaries include the Fox River, which joins it in Edwards County; the Elm River, which joins it in Wayne County; and the Skillet Fork, which joins it in White County.

• List of Illinois rivers
• Watersheds of Illinois