In 2003, Bennett joined the improv/sketch group Commedus Interruptus along with Kyle Mooney and Nick Rutherford. In 2007, after graduation, Mooney, Rutherford, and Bennett joined with editor/director Dave McCary to form the sketch group Good Neighbor. The group received praise from comedian Louis C.K. and director Steven Spielberg, who sent Mooney, Bennett, Rutherford, and McCary a personal acknowledgement after being impressed with the Hook parody, Unbelievable Dinner. He complimented the sketch and encouraged the group to continue making funny movies.
In 2011 Bennett created the fake news political talk show Fresh Perspectives, which helped him land his AT&T commercials interviewing children.
In March 2013 Bennett appeared in an episode of Last Man Standing, and that August voiced a character for FOX ADHD's Axe Cop. That same year Good Neighbor produced a pilot for Comedy Central with Adam McKay's Gary Sanchez production company, though it was not picked up as a series, in light of the move of three of the troupe's four members to New York City to star on Saturday Night Live. They debuted on SNL in September of that year, along with McCary as a director.
That same year Bennett completed work on the independent filmIntramural, and co-created the web series Theatre of Life, in which he and Rutherford film unsuspecting pedestrians and voice-over their thoughts and dialogue.