Mooney’s Marshall Middle School class chose him as the most likely to become a television star. He graduated from Scripps Ranch High School in 2003, where he won Best Actor as Prospero in Shakespeare’s The Tempest and was hailed as class clown. Mooney studied film at the University of Southern California. There, he performed improv and sketch comedy with collegiate group Commedus Interruptus. After a six-week audition process in 2003, the three new members added to Commedus were Kyle Mooney, Beck Bennett, and Nick Rutherford.

Mooney started his personal YouTube channel (simply called “kyle”) in September 2005, where he posted short comedy sketches. The channel was active from January 2011 to August 2013. He was also a member of the channel GoodNeighborStuff, along with Beck Bennett, Nick Rutherford and Dave McCary. The channel was active from May 2007 to May 2011.

In 2007, Mooney, Bennett, and Rutherford came together to form the sketch comedy group Good Neighbor, along with Mooney’s friend, director and editor Dave McCary. Bennett and Dave McCary joined Mooney on SNL in 2013 (as a performer and director, respectively), and Rutherford was hired as a writer the following year. In 2014, Good Neighbor was featured on NewMediaRockstars’ Top 100 Channels, ranked at #98.

On September 28, 2013, Kyle Mooney made his debut on Saturday Night Live as a featured player. At the start of the forty-first season, Mooney was upgraded to repertory status.