Spears was born in Chicago, Illinois. His mother Doris Spears is a jazz singer. Spears moved to New Jersey at age 11 and attended Arthur M. Judd Elementary School. He became a comedian at 14, performing stand-up comedy in various comedy clubs in New York City. He was expelled for fighting during his sophomore year in North Brunswick Township High School in North Brunswick Township, at age 17. Spears started doing his own comedy routine around his hometown.

Spears' first television appearance was on Russell Simmons's Def Comedy Jam, followed by It's Showtime at the Apollo (1987). He moved to Los Angeles in 1992, landed a recurring role on A Different World (1993) and became a regular at The Comedy Store, The Improv and The Laugh Factory. Other television credits include Crosstown Traffic, The Adventures of Brisco County, Jr. (1993) and Soul Train. At 16, Spears landed a part in the movie Malcolm X. Shortly thereafter, he was cast in a starring role opposite Glenn Frey in South of Sunset (1993). Spears's other movie appearances include Home of Angels (1994), The Pest (1997), Jerry Maguire in which he played Teepee, brother of Rod Tidwell (1996), Out-of-Sync (1995), and The Proud Family (2003).

He joined the cast of MADtv during its 3rd season in 1997, and he left at the end of its 10th season in 2005. During his stay, he created characters such as comedienne Belma Buttons (co-host of fictional BET show "Reality Check"), Dollar Bill Montgomery (a host of an urban parody of Politically Incorrect called "Real **********ing Talk with Dollar Bill Montgomery"), James Brown Jr. (co-host of Cabana Chat), and controversial rapper Emcee Esher. He is well known for his impressions of celebrities, including rappers Jay-Z, LL Cool J, DMX, and Snoop Dogg and actors Robert De Niro, Al Pacino, Sylvester Stallone, Denzel Washington, Eddie Murphy, and Arnold Schwarzenegger, as well as fellow comedian Paul Mooney.

Spears appeared on a 2nd season episode of Mind of Mencia, which parodied Jamie Foxx's role in Kanye West's music video for "Gold Digger." He also appeared in the 2006 movie Hood of Horror. Spears performed in the TV series The Underground and voiced the character Wizard Kelly in the animated television series The Proud Family. Spears appeared on the Covino and Rich radio talk show and criticized rapper Soulja Boy Tell 'Em. He challenged Soulja Boy Tell 'Em to a rap battle, claiming he would win easily. Spears appeared in two episodes of Frank Caliendo's sketch comedy show Frank TV as Shaquille O'Neal. Spears has signed with Fabb Vision Network, starring as host of his new show "The Underground," which is shot in Columbus, Ohio. The show was due to start broadcasting in September 2010. He appeared alongside Cedric the Entertainer and other comedians in the All Star Comedy Jam in 2009. His 2011 stand-up comedy special Aries Spears: Hollywood, Look I'm Smiling was shown on Showtime.