Brock Peters was born George Fisher in New York City, the son of Alma A. (née Norford) and Sonnie Fisher, a sailor. He was of African descent. Peters set his sights on a show business career early on, at the age of 10. A product of New York's famed High School of Music and Art, Peters initially fielded more odd jobs than acting jobs as he worked his way up from Harlem poverty. Landing a stage role in Porgy and Bess in 1949, he quit physical education studies at City College of New York and went on tour with the opera.
Peters made his film debut in Carmen Jones in 1954, but began to make a name for himself in such films as To Kill a Mockingbird and The L-Shaped Room. He received a Tony nomination for his starring stint in Broadway's Lost in the Stars.
He sang background vocals on the 1956 hit "The Banana Boat Song (Day-O)" by Harry Belafonte, as well as on Belafonte's 1957 hit, "Mama Look a Boo-Boo". He also sang on the song "Where" from Randy Weston's 1959 album Live at the Five Spot and shared vocal duties with Martha Flowers on Weston's album of the following year, Uhuru Afrika.
He was a special guest star in the third season of The Streets of San Francisco, playing the character "Jacob" in the episode called "Jacob's Boy" (1974).
In the film Abe Lincoln, Freedom Fighter (1978), Peters plays Henry, a freed black slave who is falsely accused of robbery but, defended by Abraham Lincoln, is found not guilty due to the fact he has a damaged hand and could not have committed the crime. In To Kill a Mockingbird, Peters plays Tom Robinson, a black man falsely accused of raping a white girl, whom Atticus Finch shows could not have committed due to the fact his hand (and arm) were damaged.
In radio, Peters was the voice of Darth Vader for the National Public Radio adaptation of the original Star Wars trilogy. He also played the role of a Colonial prosecutor trying to make a murder case against Starbuck in an episode of the original Battlestar Galactica.
He also worked in the films Star Trek IV: The Voyage Home and Star Trek VI: The Undiscovered Country as Fleet Admiral Cartwright of Starfleet Command. Peters also portrayed Joseph Sisko, father of Deep Space Nine's commanding officer, Benjamin Sisko, on Star Trek: Deep Space Nine.
In 1993, he was a member of the jury at the 43rd Berlin International Film Festival.
In early 2005, Peters guest-starred in an episode of JAG during its final season, "Bridging the Gulf", season 10 episode 15.
Peters worked with Charlton Heston on several theater productions in the 1940s and 1950s. The two became friends and subsequently worked together on several films, including Major Dundee, Soylent Green, and Two-Minute Warning.
He also voiced Soul Power in the animated series Static Shock (2000–2004).
Brock Peters read Gregory Peck's eulogy at Peck's funeral in 2003. Brock's character, Tom Robinson, was defended by Peck's Atticus Finch in 1962's To Kill a Mockingbird.