Born Rex Elvie Allen to Horace Allen and Faye Clark on a ranch in Mud Springs Canyon, forty miles from Willcox, Arizona, Rex Allen would grow up to become a popular entertainer known as "The Arizona Cowboy." As a boy he played guitar and sang at local functions with his fiddle-playing father until high school graduation when he toured the southwest as a rodeo rider. He got his start in show business on the East Coast as a vaudeville singer then found work in Chicago as a performer on the WLS Radio program, National Barn Dance. In 1948 he signed with Mercury Records where he recorded a number of successful country music albums until 1952 when he switched to the Decca label where he would continue making records into the 1970s.

When singing cowboys such as Roy Rogers and Gene Autry were very much in vogue in American film, in 1949 Republic Pictures in Hollywood gave him a screen test and put him under contract. Beginning in 1950, Allen starred as himself in nineteen of Hollywood's western movies. One of the top-ten box office draws of the day, whose character was soon depicted in comic books, on screen Allen personified the clean cut, God-fearing American hero of the wild west who wore a white Stetson, loved his faithful horse named "Koko" and had a loyal buddy who shared his adventures. Allen's comic relief sidekick in first few pictures was Buddy Ebsen and then character actor, Slim Pickens.

Over his career, Rex Allen wrote and recorded many songs, a number of which were featured in his own films. Late in coming to the industry, his film career was relatively short as the popularity of westerns faded by the mid 1950s. He has the distinction of making the last singing western in 1954. As other cowboy stars made the transition to television, Allen tried too, cast as Dr. Bill Baxter for a half-hour weekly series called Frontier Doctor. Allen was gifted with a rich, pleasant voice, ideally suited for narration and was able to find considerable work as a narrator in a variety of films especially for Walt Disney Pictures wildlife films and TV shows. He also was the voice of the father on Disney's Carousel of Progress , which was presented at the 1964 World's Fair and is now at Walt Disney World . He was also the voice behind Purina Dog Chow commercials for many years.

For his contribution to the motion picture industry, Rex Allen was given a star on the Hollywood Walk of Fame at 6821 Hollywood Blvd. In 1983, he was inducted into the Western Performers Hall of Fame at the National Cowboy & Western Heritage Museum in Oklahoma City, Oklahoma.

In 1989 his life story was told in the book Rex Allen: "My Life" Sunrise to Sunset - The Arizona Cowboy written by Paula Simpson-Witt and Snuff Garrett.

Rex Allen died in 1999 in Tucson, Arizona from injuries received when his caretaker accidentally ran over him in the driveway of his home. Cremated, his ashes were scattered near the Rex Allen Museum and Willcox Cowboy Hall of Fame in Willcox, Arizona where most of his memorabilia is on display. A few months before his death, Allen gave an extensive interview on his days at WLS radio to announcer and producer Jeff Davis for the 75th Anniversary History of WLS Radio program, which was broadcast after Allen died. That segment of the program was dedicated to his memory.

His son, Rex Allen Jr. was also a successful singer, with several country hits in the 1970s.

See also: Other notable figures in Western films