A stand-up comedian, actor, and producer
Kennedy, the youngest of six children, was born and raised in Upper Darby Township, Pennsylvania, a suburb of Philadelphia, to a machinist father and an accountant and paralegal mother and was raised Catholic. He attended and graduated from Monsignor Bonner High School in 1988. After studying acting in college, he began his career as a Hollywood extra and honed his skills at voice impersonations.
This skill led to, among other things, an unorthodox success in the way of creating a false persona, screen agent "Marty Power" (a fictitious person). Posing as Marty Power over the telephone, Kennedy attracted the attention of real agents and managers who would later book his performances. He eventually landed his first major motion picture role in the late 1990s when he was cast as Randy Meeks in the Scream series of horror films. As a performer of stand-up comedy, he is best known for his sketch performances on his television reality show, The Jamie Kennedy Experiment (which became the WB Network's highest ranking new show in 2002, but which was cancelled in April 2004 due to falling ratings). In 2006, Jizzy Entertainment released Unwashed: The Stand-Up Special.
He formed a production company called Wannabe Producers with Josh Etting through which he has produced the shows The Jamie Kennedy Experiment, Blowin' Up as well as The WB shows The Starlet and Living with Fran. Following Malibu's Most Wanted (2003), which he both wrote and starred in, Kennedy co-wrote the MTV show Blowin' Up (2006) featuring his friend Stu Stone. While working on Malibu's Most Wanted, Kennedy had ghostwriter Ellen Rapaport write a pseudo-comedic autobiography entitled, Wannabe: A Hollywood Experiment. The book chronicles his life in Hollywood as he attempts to become a star. It gives background on his life and family, and quickly dives into his adventures. It tells of such things as Kennedy's living conditions in the Hollywood slums, his beat up car, his kidney issues, and funky characters throughout the story.
He has also performed minor roles in a number of other films. Kennedy lent his voice as a celebrity in the videogame ESPN NFL 2K5 as a celebrity adversary with his own football team, the Upper Darby Cheesesteaks and he is also unlockable as a Free Agent tight end in season mode.
He hosted the Activision press conference at E3 2007, where his position as emcee was criticized for his patronizing jokes about the audience and inappropriate commentary as the new Tony Hawk game was displayed.
He often appears in movies with actor Kal Penn (Harold & Kumar Go to White Castle). In the movie, Malibu's Most Wanted, Kennedy played B-Rad and Kal Penn played a Middle Easterner who was in his group, and in Son of the Mask, Kal Penn played a friend of Kennedy's character. Kennedy also had a small, uncredited cameo in Harold & Kumar Go to White Castle, a film that starred Penn.
He currently plays psychology professor Eli James in the CBS drama Ghost Whisperer 
He resides in the Griffith Park neighborhood of Los Angeles.