Roundtree was born in New Rochelle, New York, the son of Kathryn, a nurse and housekeeper, and John Roundtree, a caterer, garbage collector, and Pentecostal Church elder. Richard Roundtreee graduated from New Rochelle High School in 1961 and starred on New Rochelle High's undefeated and nationally ranked football team in 1960. He attended Southern Illinois University. Roundtree was diagnosed with the rare form of male breast cancer in 1993 and underwent a double mastectomy and chemotherapy.
Roundtree was a leading man in early 1970s Blaxploitation films. He also played a role in the 1977 television series Roots, in the role of the slave Sam Bennett. He portrayed Dr. Daniel Reubens on Generations from 1989-1991. Prior to becoming an actor, he was a football player and a model. Although Roundtree worked through the 1990s, many of his more recent films were not well-received, but he was able to find success in stage plays.
Since 1990, however, he reemerged as a cult icon. Roundtree appeared in David Fincher's critically acclaimed 1995 movie Se7en, the 2000 remake of Shaft as John Shaft's uncle, and guest-starred in several episodes of the first season of Desperate Housewives as an amoral private detective. He also appeared in 1997's George of the Jungle, as well as playing a high school vice-principal in the 2005 (General release: 2006) movie Brick Panic Button 2007 film. His voice was also utilized as the title character in the hit Play Station game Akuji the Heartless, where Akuji must battle his way out of the depths of hell at the bidding of the Baron.
In 1997, Roundtree had a leading role in the short-lived FOX ensemble drama 413 Hope St. He portrayed Booker T. Washington in the 1999 television movie Having Our Say: The Delany Sisters' First 100 Years.
He has appeared in the television series Heroes as Simone's terminally ill father, Charles Deveaux. Next he appeared in an episode of Lincoln Heights. Most recently, Roundtree has a supporting role in the 2008 Speed Racer film as a racer-turned-commentator who is an icon and hero to Speed.