Blue John Canyon is a slot canyon in eastern Wayne County, Utah, United States, southwest of the Horseshoe Canyon Unit of Canyonlands National Park and 42 miles south of Green River. It is a tributary of the Horseshoe Canyon, running northeastwards from the Robbers Roost Flats.
Blue John Canyon includes the site of the 2003 accident in which climber Aron Ralston was forced to amputate his forearm after being trapped by a boulder, as recorded in his autobiography Between a Rock and a Hard Place and the film 127 Hours.