During his time on the show, he played a recurring character that led to a feature film adaptation, MacGruber (2010), and a streaming television limited series in 2021.

After obtaining a history degree from the University of California, Los Angeles and becoming a financial broker like his father, Forte changed his career path to comedy and took classes with the improv group The Groundlings.

He has provided voice-work for the Cloudy with a Chance of Meatballs films (2009–2013), My Life as a Courgette, Get Squirrely (2016), Luis & the Aliens (2018), The Willoughbys and Scoob!

[4] The son of artist and former schoolteacher Patricia C. (née Stivers)[5][6] and financial broker Orville Willis "Reb" Forte III.

[9] He was interested in comedy from a young age, growing up idolizing comedians Peter Sellers, David Letterman, and Steve Martin as well as the sketch-comedy television series Saturday Night Live.

[9] Forte was "a laid-back teen with a lot of friends", and a member of the varsity football and swim teams at Acalanes High School in Lafayette where he graduated in 1988.

After high school, he attended the University of California, Los Angeles, where he was a member of the Lambda Chi Alpha fraternity and completed a degree in history.

[13] Forte began taking classes at The Groundlings in Los Angeles, an improvisational and sketch comedy troupe and school, while tutoring children to make ends meet.

"[15] Forte left New York and returned to Los Angeles, where he began performing with the Groundlings' Main Company, with Cheryl Hines, Jim Rash, and Maya Rudolph.

[14] At his audition for SNL, he performed multiple original characters, including Tim Calhoun, a speed reader, a prison guard, in addition to impressions of singer Michael McDonald and actor Martin Sheen.

[15][17] After Will Ferrell left Saturday Night Live the following spring, Forte joined the cast, premiering at the beginning of the show's twenty-eighth season in the autumn.

Forte's favorite sketch on the show was one in which he played a motivational coach alongside football star Peyton Manning.

He often spent long hours crafting his sketches for the program, missing deadlines, but his pieces were usually received warmly at table reads.

[21] Forte's best-known character on SNL was MacGruber, a special operations agent who is tasked in each episode with deactivating a ticking bomb but becomes distracted by personal issues.

In 2009, the sketches were spun off into a series of commercials sponsored by Pepsi premiering during Super Bowl XLIII which featured the actor behind MacGyver, Richard Dean Anderson, as MacGruber's father.

[22] After the success of the advertisements, creator Lorne Michaels approached Forte, Taccone, and writer John Solomon with the idea to produce a MacGruber film.

"[19] His celebrity impressions included George W. Bush, Tom DeLay, John Edwards, Timothy Geithner, Newt Gingrich, Chad Lowe, Zell Miller, David Petraeus, Harry Reid, Brian Williams, and Hu Jintao.

[22][25] It was written while simultaneously producing the weekly episode of SNL, and the show's production process left the trio deprived of sleep.

[10] Afterwards he entered what he has called a "lost period"[14] and had small supporting roles, such as Rock of Ages, That's My Boy, and The Watch, all of which were not successful.

[14] He felt scared initially, but followed Bruce Dern's acting advice to "look for the truth" in each scene—in other words, "In every scene, you're just trying to play it as honestly and as real as you can.

"[15] Forte began working on The Last Man on Earth, a sitcom, with longtime collaborators Phil Lord and Christopher Miller in 2013.

He felt odd being in charge of its writing team (composed of longtime friends), and awkward at delegating tasks, so much so that he would end up doing the work himself.

[34] In 2016, Forte played Hulka, a low-level weed dealer, in the comedy Keanu, starring Jordan Peele and Keegan-Michael Key.

[35] In 2018, he played National Lampoon magazine co-founder Douglas Kenney in the Netflix biographical film A Futile and Stupid Gesture.

[38] In 2021, Forte starred in Sweet Tooth, reprised his role as MacGruber in a TV series on Peacock, and began voicing Wolf Tobin in the animated sitcom The Great North.

Forte was a childhood friend of camp founder Stephen Wampler[41] and previously the national spokesman for SciEyes, a non-profit organization created to support research, training and public education in stem cell biology and to further the field by recognizing and supporting its potential for creating new therapies for the treatment of blinding and debilitating eye diseases.

Forte bought the home in 2002, just two weeks before joining the cast of Saturday Night Live which required him to move to New York City.