Allen was an American film and television actor, singer and songwriter, known as "the Arizona Cowboy". He became famous in the 1950s as one of the last singing cowboys, and as the narrator of many Disney nature and Western productions. He grew up on a homestead about 40 miles from Willcox.
The museum includes photos, movie posters, cowboy outfits, records, musical instruments and other memorabilia.
The Willcox Cowboy Hall of Fame features portraits of area old-time cowboys who worked in the ranch industry.
Across the street from the museum is a bronze statue of Rex Allen.