Herman August Wilhelm Katt was born in Brooklyn, New York. His parents were German immigrants. Reared in New York City, he attended Pratt Institute, calling himself William H. Katt. Tall, handsome, and a natural athlete, Williams became a professional swimmer, performing in underwater shows. During this time he landed a walk-on role as a theatre usher in King Kong (1933). He enlisted in the United States Army during World War II, but was discharged before the end of the conflict and became an actor. He made his credited debut in The Blue Room in 1944, using the professional name Bill Williams. His first starring role opposite Susan Hayward in Deadline at Dawn(1946) made him a star.
Williams had appeared in ten films before he landed the lead role in The Adventures of Kit Carson, which ran for 104 episodes. After the series ended, Williams' star power quickly fizzled out. It was briefly revived in 1957 when he co-starred with Betty White in television's Date with the Angels. Williams played Federal agent Martin Flaherty in The Scarface Mob (1959), the pilot for ABC's The Untouchables. In the series, however, the role went to Jerry Paris. In 1958, Williams turned down the lead in Sea Hunt because he believed than an underwater show would not work well on television. Lloyd Bridges accepted the part and turned it into a hit. Williams then starred as a former Navy frogman in Assignment: Underwater, which ran for just one season. He played a variety of roles on thePerry Mason show, in which his wife Barbara Hale co-starred with Raymond Burr. In a 1962 episode he played the defendant Mike Preston in "The Case of the Crippled Cougar". In 1965 he played murderer Charles Shaw in "The Case of the Murderous Mermaid." He also made guest appearances on television and worked in low-budget science fiction films until his retirement in the early 1980s.
Williams married actress Barbara Hale in 1946. They had met during the filming of West of the Pecos and would have two daughters, Jodi and Juanita, and a son, actor William Katt.
Bill Williams died of a brain tumor at age 77 in 1992.
For his contribution to the television industry, Bill Williams has a star on the Hollywood Walk of Fame. It is at 6161 Hollywood Blvd.