He has had notable supporting roles in films such as Romeo + Juliet (1996), Enemy of the State (1998), Bowfinger (1999), Three Kings (1999), Boiler Room (2000), Max Keeble's Big Move (2001), and Good Deeds (2012).

Following Malibu's Most Wanted, in which he both wrote and starred, Kennedy co-wrote the MTV show Blowin' Up (2006) featuring his friend, Stu Stone.

Kennedy lent his voice to the videogame ESPN NFL 2K5 as a celebrity adversary with his own football team, the Upper Darby Cheesesteaks.

His stint as Activision's emcee at Electronic Entertainment Expo 2007, however, drew much criticism not only for his ignorance of the industry, but also for appearing to perform drunk as he insulted the audience.

[6] In a video uploaded to YouTube on June 14, 2021, Kennedy claimed that Activision had scrapped his script at the last minute and he was ad-libbing his jokes while suffering from burnout.

[7] While working on his film Malibu's Most Wanted, Kennedy wrote an autobiography titled, Wannabe: A Hollywood Experiment.

His film Lost & Found in Armenia, in which he plays an American tourist who ends up in an Armenian village, accused of being a Turkish spy, later opened to select theatres on June 7, 2013.

[16] Kennedy played NARAL Pro-Choice America founder Larry Lader in the 2020 film Roe v. Wade, which stars a predominantly conservative ensemble cast.

[17] In an interview with The Daily Beast, which noted the film depicts Lader as "a shady figure pulling strings from behind the scenes who treats abortions as a money-making operation," Kennedy said he personally supports abortion rights and appeared in the film to perform in a dramatic role that he is not normally offered, and that, "it’s also not fair for people to think that because I’m in a project with them that I’m like that, or that I believe in this stuff.