He began living on his own at the age of 18. He briefly attended Los Angeles Valley College, a community college, where he was placed on academic probation before dropping out to work in a series of jobs, including carpet cleaner, carpenter, boxing instructor, and traffic school instructor. Although broke, Carolla, his friends, and roommates owned a 1963 Cadillac limousine.

During his earlier years, Carolla played Pop Warner football for seven years; he later suggested that being involved in Sports saved him from a chaotic home life. During his senior year at North Hollywood High School, Carolla distinguished himself in football. In December 1981, he was named to the First Team Offensive Line, Central Valley League, one of 8 leagues at the time in the LA City Section of the California Interscholastic Federation.

In the early 1990s, Carolla studied improvisational comedy with The Groundlings and was a member of the ACME Comedy Theatre troupe.

In 1994, Carolla volunteered his services as a boxing trainer to prepare Jimmy Kimmel for a bout being staged by KROQ-FM's morning radio program Kevin and Bean. Kimmel was a regular on the show as "Jimmy the Sports Guy" and he was set to fight another KROQ personality in a boxing exhibition which was being billed as the "Bleeda in Reseda." Carolla parlayed this opportunity into a long-running friendship and Business partnership with Kimmel as well as a recurring role on Kevin and Bean as cranky woodshop Teacher, Mr. Birchum.

In October 1995, after being signed to the william Morris Agency by Mark Itkin, Carolla was offered the job of co-hosting the radio call-in show Loveline. His co-hosts were the physician Drew Pinsky ("Dr. Drew") and Riki Rachtman. Carolla received the offer after Pinsky heard him on Kevin and Bean (Rachtman left the show the following year.) Loveline is broadcast on KROQ-FM in Los Angeles and is syndicated nationwide on the Westwood One radio network.

Carolla and Drew Pinsky co-wrote (with Marshall Fine) the self-help book The Dr. Drew and Adam Book: A Survival Guide to Life and Love, published in 1998. The book is a compilation of some of the advice the pair compiled while producing Loveline.

After co-hosting (with Dr. Drew) a television version of Loveline on MTV during the late 90s, Carolla began his first original television series with The Man Show, along with partner and close friend Jimmy Kimmel, on Comedy Central from 1999 to 2003. He left The Man Show at the same time as Kimmel, after having been reportedly offered $50,000 per episode to stay on. Carolla has continued his work with Kimmel as a Writer and guest on Jimmy Kimmel Live!. He also appeared on an episode of Space Ghost Coast to Coast around this time.

Carolla and Pinsky received a Sexual Health In Entertainment (SHINE) Award from The Media Project in 2000 for "incorporating accurate and honest portrayals of sexuality" in the talk show category for Loveline.

While the format of the program was primarily a call-in show where listeners would ask questions about sex and relationships, Carolla would often spend much of the show ranting about various topics, from fart jokes to extended parodies of radio morning shows, including mocking the format's penchant for useless and repetitive weather and traffic reports. In contrast to the reserved, thoughtful Pinsky, Carolla served as the loud, funny side of the show. Carolla's character was described by one reviewer as "a toned-down version of Howard Stern minus the huge ego". On September 25, 2001 Carolla and Jimmy Kimmel both had filled in for Howard Stern's head Writer Jackie Martling after Martling's departure from the show in March 2001. Carolla had mentioned in various interviews and on his podcast that he was offered the job to replace Jackie Martling, but turned it down primarily due to Stern's show being located in New York as well as his commitment to Loveline.

On September 28, 2002, Carolla married Lynette Paradise. Lynette gave birth to their first children, twins Natalia and Santino "Sonny" Richard Carolla on June 7, 2006. On The Adam Carolla Show, Adam repeatedly mentioned the birth was originally scheduled for June 6, but that he and Lynette decided to push it back one day as to avoid the symbolic 666 (06–06–06).

Carolla has occasionally made generalizations about various groups, leading to criticism. For Example, in a late-2003 Loveline episode, Carolla said that Hawaiians are "dumb," "in-bred," "retarded, " people who are among the "dumbest people we have." The comments were met with anger in Hawaii and resulted in Loveline's cancellation on Hawaiian affiliate KPOI.

Also in 2005, Carolla was featured in a home remodeling program called The Adam Carolla Project wherein he and a crew of old friends renovated his childhood home. The 13 episodes aired on the cable channel TLC (The Learning Channel) from October through December 2005. The house was then sold for 1.2 million dollars.

In 2006, Carolla appeared on the special summer series Gameshow Marathon as a Celebrity panelist on the Match Game episode.

Carolla and partner Daniel Kellison are the heads of Jackhole Productions. The two created the television show Crank Yankers for Comedy Central, which revived the Mr. Birchum character. (The show premiered in 2002 on Comedy Central and returned to MTV2 on February 9, 2007, running again until March 30, 2007. The show screened in Australia on SBS Television and The Comedy Channel between 2003 and 2008.)

In 2003, he appeared in Windy City Heat as himself. In 2006, Carolla finished work on The Hammer, a semi-autobiographical independent film he co-wrote and co-produced, in which he stars opposite Heather Juergensen. The film is based loosely on his own life and is filmed at a gym he helped build with his co-star, Ozzie, played by Oswaldo Castillo, his friend in real life whom he met while building the gym when they both worked in construction. The film made its world premiere at the 2007 Tribeca Film Festival in New York City and shortly thereafter received a positive review in Variety. The film was released on March 21, 2008. The film is rated 80% on Rotten Tomatoes.

On October 22, 2009, it was reported in Variety that Carolla had struck a deal with NBC to produce a half-hour pilot for a sitcom. The report was later confirmed on January 4, 2010, and was the first comedy pilot ordered by NBC for the season. The untitled project, written by Carolla and Kevin Hench, was a single-camera endeavor that starred Carolla as a contractor and Father who attempts to rebuild his life after his wife leaves him. Carolla was set to executive produce the NBC project along with frequent collaborators Kimmel and Hench, as well as his agent James "Babydoll" Dixon, Jon Pollack from 30 Rock, Gail Berman, Daniel Kellison, and Lloyd Braun. Universal Media Studios, BermanBraun, and Carolla and Jimmy Kimmel's own Jackhole Industries.

In 2010, Carolla posed for the NOH8 campaign. In August 2011, Carolla released a podcast where he mocked a petition to the producers of Sesame Street that demanded Bert and Ernie get married on air. He said on air that gay Activists should "[j]ust get married, and please shut up" and that "Y.U.C.K." would be more memorable acronym than LGBT, and referring to transgender people he asked: "When did we start giving a shit about these people?"

Carolla's The Car Show debuted on Speed TV July 13, 2011. Appearing Wednesdays at 10 pm Eastern, it featured Carolla as the host, along with Dan Neil, John Salley, and Matt Farah. It had a format similar to Top Gear, mixing car reviews, tests and humor. The show was initially met with largely positive reviews from car enthusiasts and comedy fans. Talk show host and Comedian Jay Leno called The Car Show, "...a lot of fun." The Car Show was cancelled after one season, after undergoing format changes due to low ratings, as Carolla mentioned on his podcast January 13, 2012.

In June 2012, Carolla became the target of charges of sexism due to his remarks during an interview published in the New York Post:

Carolla won the 2013 Pro/Celebrity Race as a professional and the 2012 Pro/Celebrity Race at the Toyota Grand Prix of Long Beach as an amateur. The race was run on April 14, 2012 and was broadcast on Speed TV. In 2013, Carolla again competed in the Toyota Grand Prix race, this time he raced as a pro-driver. Carolla finished first in the Pro category in the 2013 race Carolla has previously participated in the race in 2010 and 2003. He finished ninth among 19 racers (fifth among the ten celebrities) in 2010 despite being regarded as a pre-race favorite. He is also a serious automobile collector with over 20 cars. His collection includes several Lamborghinis from the 1960s and early 1970s, including two Miuras (of 764 examples ever produced), one of which he has loaned to the Petersen Automotive Museum in Los Angeles, two 400GT 2+2s (of 247 units produced) and a 1965 350GT (one of 135 built). At least one Ferrari and Aston Martin and several vintage race cars round out the collection.

The show premiered on March 9, 2014, to 1.2 million viewers, the largest audience for a series debut on Spike since Coal in March 2011. The show was cancelled in 2015.

In 2017, Carolla and Dennis Prager began filming No Safe Spaces, a documentary about political correctness at universities.

Carolla's latest book is Daddy, Stop Talking!: And Other Things My Kids Want but won't be Getting, in which Carolla writes about modern parenting. Carolla describes what he believes adults must do if they don’t want to have to support their kids forever. Carolla uses his own childhood as a cautionary tale, and decries helicopter parenting.