Born in Kansas City and raised in St. Louis, Ellie Kemper attended John Burroughs School, where her drama teacher was actor Jon Hamm. She went on to attend Princeton, where she was part of Quipfire!, an improv group, and the Princeton Triangle Club, a touring musical theater comedy troupe. Kemper eventually moved to New York, where she performed with the People's Improv Theatre and with Upright Citizen's Brigade, and appeared in bits on shows like Late Night with Conan O'Brien and The Colbert Report. In July 2009, she was named one of Variety magazine's "10 Comics to Watch." As a writer, Kemper's work has been featured in The Onion, McSweeney's, and The Huffington Post.

Kemper's break in television came after she auditioned for a role in Parks and Recreation. She didn’t get the role, but she did get a call back for a part on The Office, a show with the same creators as Parks.  Originally intended to play receptionist Erin Hannon for just four episodes in season five, she ended up being signed as a regular and stayed with the show until it ended. In 2011 came Kemper's breakout film role in Bridesmaids, alongside Kristen Wiig, Maya Rudolph, and Melissa McCarthty. She's since starred in films including 21 Jump Street, Laggies, and They Came Together. 

Currently, Kemper can be seen in the Netflix original comedy Unbreakable Kimmy Schmidt, created by Tina Fey and Robert Carlock. Kemper stars as the titular Kimmy Schmidt, a woman trying to start a new life in New York City after being rescued from a doomsday cult.