Little River Canyon is a National Preserve in the United States located on top of Lookout Mountain near DeSoto state park and Fort Payne, Alabama. The 15,288 acre national preserve was created by Congress in 1992 and protects the Little River, what is sometimes said to be the longest mountaintop river on the continent.

The canyon was historically called May′s Gulf and the usage of the word gulf is a common term throughout the Cumberland Plateau for what other areas would call a canyon. Before 1992, when the park was assigned to the National Park Service, the canyon area formed the southernmost unit of DeSoto State Park in Alabama.

There are currently few visitor facilities operated by the National Park Service within the preserve. There is a day-use area at the mouth of the canyon where a campground was once operated, but now, the area only provides places for picnics and is a popular swimming location. DeSoto State Park, operated by the Alabama State Park System, is located north of national preserve and has a lodge, restaurant, several campgrounds, and other facilities.

The river is said to be among the cleanest and wildest waterways in the South, and except for a small and derelict hydroelectric project at DeSoto Falls on the West Fork near Mentone, Alabama the Little River is undammed.

Sandstone cliffs tower up to 600 feet (180 m) above the narrow canyon floor, frequently visible from the 23-mile (37 km) scenic drive known as the Little River Canyon Rim Parkway.

The Little River Canyon Rim Parkway and travels along parts of: AL SH 176, Dekalb County Road 148, and Cherokee County Road 275. This Rim Parkway is along the western side of the canyon rim. The northern half of this road was built under federal supervision in the New Deal era. The southern half was built by local authorities.