Mazer's family left Kiev, emigrating before his first birthday. He grew up in Brooklyn, New York. He received a BA at University of Michigan before being drafted. During World War II, he served the majority of his time in the Armed Forces-Air Force Transport Command in the Pacific theatre.

After returning home, he married Dora Sudarsky ("Dutch"), his pre-war sweetheart. They had three children. Their marriage lasted 50 years, ending with her death from cancer in 1996, and Mazer has never remarried.

Early work

Mazer's broadcasting career began in 1947, when he was the commercial announcer on the CBS William L. Shirer Newscast, as well as the commercial announcer for the soap opera, When a Girl Marries.

His career as a sportscaster began in Buffalo, New York in 1948, where he signed on as sports director for WGR radio and served as principal sports anchor for WGR-TV from the time that station signed on in 1954 through the early 1960s. With years of play-by-play and sports commentary in Buffalo under his belt, Mazer arrived in New York City in 1964 when WNBC went to its first all-talk format. His show was one of the pioneer examples of the modern sports talk show in America.

After filling in for Hugh Downs on the NBC game show Concentration, he was given his own show, Reach for the Stars, in January 1967, but the show was quickly cancelled.

National sportscasting and announcing

Mazer served as a color analyst and intermission host, working alongside Dan Kelly on CBS' National Hockey League coverage from the late sixties until the early seventies, broadcasting the Stanley Cup playoffs a few times. Golf was another Mazer specialty on NBC, including the U.S. Open and Bing Crosby tournaments in the mid-1960s. ABC used Mazer for its regional New York football lineup in the late '60s. During the '60s and '70s, Mazer did much voice-over commercial work, from L&M Cigarettes, Kodak, Ford automobiles to Trident chewing gum, among many others.

WNEW-TV

Mazer was a sportcaster at New York's WNEW-TV (channel 5) for twenty years, ending in the early 1990s. He also co-hosted a sports program, Sports Extra, which originally teamed him up with Lee Leonard and then later with Brian Madden (1976—78), respectively. Sports Extra was considered a pioneering show for the Sunday evening "sports wrap-up" show format.

While doing sports for The 10 O'Clock News on WNEW in the late 1970s and '80s, he held a daily contest where a viewer would send in a question to "stump" Bill and would win a prize if he or she did.

WFAN (1988-1991; 2007) and WEVD (1992-2001)

Mazer hosted a WFAN sports show from Mickey Mantle's restaurant from 1988 to 1991, and returned to the station on June 30, 2007 to host an hour long show from 10—11 AM during the station's 20th anniversary celebration and reunion weekend. He was also a morning talk show host on WEVD where he expanded to a comprehensive talk format from 1992 to 2001. The show ended when WEVD was optioned to ABC's ESPN division and became sports WEPN.

Bill Mazer has appeared on the cable TV show The Leon Charney Report, as well as minor parts in movies such as Eyewitness and appearing in episodes of ESPN SportsCentury as an expert on sport figures including Gordie Howe, Lawrence Taylor, and Mickey Mantle.

WVOX-AM (2001 - 2009)

Following his departure from WEVD in 2001, Mazer launched an afternoon interview program on WVOX in New Rochelle, New York from 3—6 PM EST (available via streaming from WVOX's website), with his son Arnie serving as producer. His last show on WVOX was aired August 3, 2009, ending his tenure at the station.