Williamson was born March 4, 1960, in St. Louis, MO and named Mykelti, which means "spirit" or "silent friend" in the Blackfoot language of his grandfather’s ancestors. He was raised mainly in Los Angeles and loved acting and dancing from the time he was a child, first appearing in regional and church productions. At age 18, he went to his first professional acting audition and came away with a guest spot on an episode of the then popular buddy cop series, "Starsky & Hutch" (ABC, 1975-79). He subsequently spent the 1980s as a prolific television actor (billed as Mykel T. Williamson), with recurring character roles on Stephen Bochco’s baseball drama "Bay City Blues" (NBC, 1983) and “Hill Street Blues” (NBC, 1981-87). In 1986, Williamson had a role as a talented but wayward football player in the Goldie Hawn sports film “Wild Cats” (1986) before landing on "The Bronx Zoo" (NBC, 1987-88), Gary David Goldberg’s hour-long drama about a struggling inner-city high school. The actor enjoyed a regular cast role in the significantly more successful police drama "Midnight Caller" (NBC, 1988-1991) while building his film resume with a supporting role in the thriller “Miracle Mile” (1989) and screen time opposite Lou Diamond Phillips as a fellow police officer hunting down a serial killer in “The First Power” (1990). In 1991, Williamson snared the role of radio station manager "replacement" for Gary Sandy in the less-than-successful revival show, "The New WKRP in Cincinnati" (1991-93).
Williamson’s film career got a major boost in 1993 when he was cast as the kindly social worker who sends a troublemaking teen to work at a theme park where he then befriends a giant whale in "Free Willy" (1993), a certifiable family blockbuster. The following year, Williamson gave a breakthrough performance – arguably the defining role of his career – in the even bigger hit, “Forrest Gump” (1994). With his earnest portrayal of a Vietnam soldier with dreams of going into the shrimp business with his mentally disabled friend (Tom Hanks) only to have his life and dream cut short by the violence of war, Williamson’s iconic performance – most famously in his rattling off a litany of ways to prepare shrimp – the actor’s tear-jerking performance led to a steady stream of supporting film roles – not to mention, inspiring a chain of Bubba Gump Shrimp restaurants. Following the success of anything or one associated with the Academy Award-winning Best Picture, Williamson continued to make an impression – first as a handsome American in Paris for whom Alfre Woodard pines in "How to Make an American Quilt" (1995) followed by playing a drugged-out Mr. Wrong for a professional woman looking for love (Lela Rochon) in “Waiting to Exhale” (1995). He reprised his social worker role in the sequel "Free Willy 2: The Adventure Home" (1995), before Al Pacino cast the actor as a police detective in the well-received action drama "Heat" (1995) – most famous for bringing together Pacino and his acting rival Robert De Niro onscreen for the first time. In 1996, Williamson received positive notice for his portrayal of historic Negro League baseball player Josh Gibson in the HBO film “Soul of the Game” (1996).
The year 1997 proved to be a banner one for Williamson, who appeared in no fewer than five film and television projects. He appeared as the sidekick of a sociopathic kidnapper in Kiefer Sutherland’s gritty directorial debut "Truth or Consequences, NM" (1997) and continued the outlaw streak with the Nicolas Cage actioner “Con Air” (1997), playing one of a group of inmates involved in a mutiny aboard an aircraft transferring them between prisons. On the other side of the law, Williamson joined a heavy-hitting cast including George C. Scott, Jack Lemmon, and Ossie Davis in Showtime’s remake of the classic drama “12 Angry Men” (1997), where he gave an explosive performance as a bigoted juror. He gave another strong television performance in “Buffalo Soldiers” (TNT, 1997), starring alongside Danny Glover in the historic picture about the first all-black United States Army regiment.
While Williamson appeared on-screen in the political drama “Primary Colors” (1998) and had a starring role as an astronaut in the sci-fi feature “Species II” (1998), off-screen the actor’s career was interrupted for almost a year when he was tried for attempted manslaughter following a violent incident involving a companion of his ex-wife. Williamson was eventually acquitted of the charges and resumed his career with a slate of excellent film projects including “Having Our Say: The Delany Sisters' First 100 Years” (Showtime, 1999) in which he appeared in flashback segments as the father of a pair of extraordinary young African-American girls in turn of the century Virginia. From that Peabody Award-winning film, Williamson went on to appear alongside George Clooney in the Iraq-set “Three Kings” (1999), playing a Special Forces superior officer. Williamson enjoyed a featured role in the unfortunately short-lived Showtime series "The Hoop Life" (Showtime, 1999-2000), about the lives of fictitious professional basketball players, before co-starring as Inspector Girard in the CBS remake of the action series "The Fugitive" (2000-01).
Following his portrayal of boxing impresario Don King in the Muhammad Ali biopic, "Ali" (2001) starring Will Smith , Williamson earned an Outstanding Actor nomination from the NAACP Image Awards for his role as a slightly offbeat raconteur of a detective in the stylish but short-lived NBC drama, "Boomtown" (2002-03). Williamson had supporting roles in thrillers "After the Sunset" (2004) and “Lucky Number Slevin” (2006) and played the working class adoptive father of a teen nephew (Tip “T.I.” Harris) in the heartwarming coming-of-age-tale “ATL” (2006). He went on to play the bodyguard of a wealthy family whose son is abducted in “Kidnapped” (NBC, 2006-07), and when that show was unceremoniously cancelled despite positive reviews, Williamson began a multi-season recurring role as the disciplinarian Chief Sinclair on “CSI: NY” (CBS, 2004-). He returned to theaters in the powerful drama “Spinning Into Butter” (2009), starring alongside Sarah Jessica Parker as a journalist investigating a series of hate crimes at a small New England College where Parker’s character is the dean. Later that year, Williamson also had small roles in the blaxploitation film parody “Black Dynamite” (2009) and “Ball Don’t Lie” (2009), a coming-of-age story of a foster teen who finds security and acceptance on the basketball court.