She was born in Westport, Connecticut to actor Larry Kenney, who is best known for his classic voiceover work.
Kerri joined with an improv comedy group called The State and in 1994 their work was picked up for a sketch comedy show on MTV. Even after the show's cancellation in 1995 (after three seasons) Kenney continued working with her fellow troupe-members. In 1996 the variety show spoof that she co-wrote and starred in, Viva Variety, was picked up by the network Comedy Central. The show ran for two seasons, not an entirely unsuccessful run for the network.
In 2000 Kenney followed in her father's footsteps, voicing the character of "Gravitina" in the children's cartoon Buzz Lightyear of Star Command. Kenney was cast as a series regular on The Ellen Show, which failed in 2001, then found some success with her "The State" cast members in a reality police show spoof called Reno 911 in 2003.
Kenney is also well known as the lead singer in the all female alternative rock band Cake Like.