King was born in Los Angeles, California, the daughter of Gloria, a special education teacher, and Thomas King, an electrician. The two divorced in 1979. She is also the older sister of actress Reina King. Regina and Reina mean "queen" in Italian and Spanish respectively. King attended Westchester High School and the University of Southern California.

King married Ian Alexander, Sr., on April 23, 1997. Their son, Ian Alexander, Jr., was born on January 19, 1996. King filed for divorce from Alexander on November 8, 2006, citing "physical abuse, drug use, and extramarital affairs".

King began her acting career in 1985 in the role of Marla Gibbs' daughter Brenda on the television series 227, a role she played until 1990. She went on to appear in the John Singleton films Boyz n the Hood, Poetic Justice and Higher Learning. In 1995, she was featured in the hit comedy Friday. In 1996, she gained fame starring in the blockbuster romantic comedy Jerry Maguire, with Tom Cruise and Cuba Gooding, Jr. This film brought King mainstream recognition in her role as Marcee Tidwell, the wife of Cuba Gooding Jr.’s character.

Soon thereafter she played Will Smith's wife in the spy thriller Enemy of the State, and was also featured in How Stella Got Her Groove Back and Disney's remake Mighty Joe Young. She continued playing feature roles in a variety of films, including Down to Earth, with Chris Rock, Daddy Day Care with Golden Globe winner Eddie Murphy, Legally Blonde 2: Red, White & Blonde with Reese Witherspoon and Sally Field, and A Cinderella Story, with Hilary Duff.

In 2004, King played Margie Hendricks, a singer in Ray Charles’ backup group The Raelettes and one of the musical legend’s mistresses, in Ray, and in 2005, she co-starred in Miss Congeniality 2: Armed and Fabulous as Sandra Bullock's tough FBI agent partner. Additionally, she is the star of the Adult Swim show The Boondocks, providing the voices for the characters Huey and Riley Freeman, as well as the feature film The Ant Bully. Most recently, she appeared in season 6 of the hit show 24 and the film This Christmas with an all star cast, such as Loretta Devine, Idris Elba, Columbus Short, and Chris Brown. In 2008, she appears in the TV film Living Proof.

King currently stars in the TNT police drama Southland, as Detective Lydia Adams. NBC originally aired the show's first few episodes and then requested new episodes. NBC, however, began airing Jay Leno's then-new talk show five nights a week in prime time, occupying the time slot "Southland" and other scripted television series had held during week nights. NBC did not feel the show could work in an earlier time slot due to its grittier nature, thus the network did not pick up the second season of "Southland". Cable network TNT believed the show would be a good fit for TNT and in January 2010, that network began airing the original NBC episodes, in addition to ordering new episodes of "Southland".

Regina King was a vocal and prominent supporter of Barack Obama in his campaign for election to the United States presidency. She traveled all across Ohio, prior to the Ohio primary, stumping for Senator Obama. She has been quoted as saying "So it's just a very grass roots way to get the word out. And you know it's how Obama started his campaign and that's how he's been winning the last few primaries, by not forgetting about the so-called little people."