Born George Montgomery Letz to Ukrainian immigrant parents in Brady, Montana, the youngest of 15 children. He was raised on a large ranch where as a part of daily life he learned to ride horses and work cattle. Letz studied at the University of Montana but because he was more interested in a career in film, he left after a year to go to Hollywood. At Republic Pictures, his cowboy skills got him stunt work and a small acting part at the age of 18 in a 1935 film, The Singing Vagabond.
He followed this with bit parts and additional stunt work as George Letz in mostly low-budget films. He was frequently cast in western films starring their number one box office draw, the singing cowboy, Gene Autry. Elevated to more important secondary roles, in 1938 he appeared as one of the six men suspected of being the titular hero in The Lone Ranger. He remained with Republic Pictures until 1940 when he signed with 20th Century Fox, which billed him as George Montgomery.
At Fox, Montgomery appeared in more westerns including The Cisco Kid and the Lady (1940) with Cesar Romero. In 1942, he played opposite Gene Tierney in China Girl, jazz musician Glenn Miller in Orchestra Wives, and Ginger Rogers in Roxie Hart. The following year, Montgomery starred with Betty Grable in the Walter Lang-directed film, Coney Island.
World War II interrupted his film career. He joined the United States Army Air Forces in 1943. On December 5, 1943, he married singer Dinah Shore, with whom he would have one child, Melissa Ann "Missy" Montgomery (b. 1948), during a marriage that lasted until 1963. George and Dinah also adopted John "Jody" David Montgomery in 1954. In 1963, Montgomery's private life made headlines when his housekeeper was charged with a failed attempt to kill him. Allegedly suffering from a fanatical attraction to her employer, the deranged woman planned to shoot Montgomery then take her own life.
As a boy, George Montgomery had developed excellent craftsmanship with wood and as an adult pastime he began building furniture, first for himself and then for a few friends. His skill was such that his hobby became a full-fledged cabinet-making business, employing as many as 20 craftsmen.
Montgomery oversaw the furniture business for more than forty years and expanded his interest to house design that saw him involved with the building of eleven homes for friends and family. His artistic instincts included learning how to sculpt in bronze. Self-taught, he sculpted upwards of 50 bronze sculptures including ones of John Wayne, Clint Eastwood, Gene Autry, Randolph Scott, and future U.S. president Ronald Reagan. His sculpture of his former wife, Dinah Shore, and their children is at the Mission Hills Country Club in Rancho Mirage, California, home to the LPGA Kraft Nabisco Championship.
Through the early 1970s, Montgomery acted in films and made guest appearances on a number of television shows, including NBC's Bonanza and The Gisele MacKenzie Show, a variety program. In the 1958-1959 season, Montgomery starred in his own 26-episode NBC Western series, Cimarron City as mayor Matt Rockford. After a career that included more than eighty feature films, Montgomery retired in 1972, making only two more minor appearances in film until his death at his home in Rancho Mirage, California, aged 84.
After cremation, Montgomery's ashes were divided and interred at Forest Lawn Cemetery (Cathedral City) near his Palm Springs home and at the Highland Cemetery in Great Falls, Montana, near his birthplace.
For his contribution to the television industry, George Montgomery has a star on the Hollywood Walk of Fame at 6301 Hollywood Blvd.