Police Sgt. Joe Monson said Tuesday the child was apparently left behind while visiting the Crazy Corn Maze in the Salt Lake City suburb of West Jordan with a large family group.
He said the boy was cold and frightened but unhurt when someone else found him at the maze Monday evening.
Staffers called on a bullhorn and searched for his family but couldn't find anyone until his mother called police Tuesday morning. Monson said she later arrived at the police station with about 10 other children.
The boy is expected to be reunited with his family.
Monson said it wasn't immediately clear how the child's disappearance went undetected, but police are investigating whether any criminal charges are warranted.