He was born to a Swedish family and taught himself ventriloquism from a pamphlet when he was only 11. A few years later he commissioned a woodcarver to make a portrait of a rascally Irish newspaperboy he knew. The head went on a puppet named Charlie McCarthy, who became Bergen's lifelong sidekick.
His first performances were in vaudeville and one-reel movie shorts, but his real success was on the radio. He and Charlie were seen at a Hollywood party by Noel Coward who recommended them for an appearance on Rudy Vallee's program that was so successful that the next year they were given their own show. They were on the air from 1937 to 1956.
For the radio program, Bergen developed other characters, notably the slow-witted Mortimer Snerd and the man-hungry Effie Clinker. The star, however, was Charlie, who was always presented as a child, albeit in top-hat, cape, and monocle, a debonair, girl-crazy, child-about-town. As a child, and a wooden one at that, Charlie could get away with double entendre that adult humans could not, even in those more-censored times.
Charlie's feud with W. C. Fields was a regular feature of the show.
Bergen and McCarthy are sometimes credited with "saving the world" because, on the night of October 30, 1938, when Orson Welles performed his War of the Worlds radio play that so panicked the nation, most of the American public had tuned in to hear Bergen and McCarthy and never heard Welles' play.
After the radio show ended, Bergen and McCarthy appeared on the TV show, Do You Trust Your Wife and also in live performance.
In addition to his work as a ventriloquist, Bergen was also an actor. He appeared as the shy Norwegian suitor in I Remember Mama (1948). He also appeared in Captain China (1949) and Don't Make Waves (1965). He and McCarthy appeared in The Goldwyn Follies (1938) and in The Muppet Movie (1979). It was his last appearance and the film was dedicated to him.
He is a member of the Radio Hall of Fame. He attended Northwestern University, but did not graduate. Later the school gave him an honorary degree as Master of Innuendo and Snappy Comeback.
Bergen was the father of actress Candice Bergen whose first performances were on the radio show, although she came to be weary of being called "Charlie's little sister".