While in Chicago, Favreau landed his first film role alongside Sean Astin as the pudgy tutor D-Bob in the classic sleeper hit Rudy (1993). Favreau met Vince Vaughn—who also played a small role in this film—during shooting. The next year, he appeared in the college film PCU alongside Jeremy Piven, and also stepped into the world of television in the 1994 episode of Seinfeld titled "The Fire" as Eric the Clown. He then moved to Los Angeles, where he made his breakthrough in 1996 as an actor-screenwriter with the film Swingers, which was Vaughn's breakthrough role as the glib and extremely confident Trent Walker, a perfect foil to Favreau's heartbroken Mike Peters. In 1997 he appeared on the popular TV sitcom Friends portraying Pete Becker, whom Monica dates for several episodes, and who competes in the Ultimate Fighting Championship.

He rejoined Piven in 1998 as part of Very Bad Things (1998). In 1999 he starred in Rocky Marciano, based on the life of the only undefeated wor