Born in Calgary, Alberta, Pat Kelly, despite his fondness for being the center of attention with his family and friends, hadn't considered going into showbusiness as a career. However, after considerable pressure from two Grade 9 classmates, he joined an acting group and was cast in a play. From that moment on, he knew he'd found his niche and acted not only in school dramas, but began volunteering and taking acting classes at the Loose Moose Theatre. By Grade 11, he was a regular Loose Moose performer and was there every weekend acting alongside his friend, Peter Oldring.
After high school, he took a year to travel through Canada, then enrolled in the drama program at the University of Lethbridge, where he began writing plays and developing his own material. But when his mother became terminally ill, he left school before graduating.
Undaunted, Kelly and Oldring co-wrote Two Guys Who Desperately Want to Be on Television in 1997 and toured Fringe Festivals with it. In Toronto, they mounted the play at a secondary theater at The Second City and received positive reviews. The Comedy Network shot the play for television and they were both hired to be part of The Second City touring Company.
When Kelly landed a role as the host of the YTV after-school program The Zone, he stopped touring. After two years on the show, he left to pursue different acting gigs and was invited back to The Second City main stage. During this time he made guest appearances on various television shows such as Screech Owls, Just for Laughs, The Gavin Crawford Show, Jonovision, the Comedy Network's Supertown Challenge and as well, became a regular on CBC's Liquid Soap.
Kelly made his feature film debut with a small role in Urban Legends: Final Cut (2000). His second film role was substantially larger, playing Dale Dodd in Intern Academy (2004), written, directed by and starring Dave Thomas.