Kattan was a member of several improv/sketch comedy troupes one of them being The Groundlings in Los Angeles. His father was an original member of the troupe. Kattan also did some minor roles on TV, including the first episode of the second season of NewsRadio, "No, This Is Not Based Entirely on Julie's Life," as a photo shop employee.

He moved to New York City to work on Saturday Night Live from 1995 to 2003. His recurring characters included Mr. Peepers, Mango, Azrael Abyss, Kyle DeMarco from The DeMarco Brothers, Gay Hitler, Suel Forrester (known for the term "dagitybo") and, most notably, one half of the Butabi Brothers with fellow SNL (and Groundlings) cast member Will Ferrell, known for their trademark head-bobbing. Kattan and Ferrell continued the characters in 1998's A Night at the Roxbury.

Kattan has made one appearance on Broadway, playing Xanthias in a production of Aristophanes' The Frogs until his replacement during previews by Roger Bart. Kattan was set to host the game show Gameshow In My Head and even filmed the pilot episode in Hollywood. However, he was replaced with Joe Rogan for the series.

Kattan appeared in a Diet Pepsi MAX commercial during Super Bowl XLII that featured "What Is Love" and had many actors in the commercial performing the Butabi head bob. In August 2009 Kattan starred in the IFC miniseries Bollywood Hero, where he portrays himself and the difficulties he faces after a career as a comic actor, trying to attain leading man status. Starting in fall of 2009, Kattan appeared in a supporting role in The Middle. Kattan plays Bob, a colleague of Frankie Heck's at Mr. Ehlert's car dealership.Kattan appeared in the May 17th episode of How I Met Your Mother as a star in a fictional movie within the show. He played himself acting as Jed Mosely, a character based on the main character Ted with an arrogant personality. In December 2011, Kattan made a guest appearance on Saturday Night Live's Christmas show, hosted by Jimmy Fallon.