Kinnunen made her Broadway debut at age 16, as a replacement for the role of Thea in
Spring Awakening. In 2010, Kinnunen was the understudy for the role of Natalie in the national tour of
Next to Normal. Following these theater performances, Kinnunen took on a number of television and film roles. She was the lead character in the film
Sweet Little Lies in 2011 and a minor character in ''
It's Kind of a Funny Story, We Need to Talk About Kevin, and The Intern''. She was next seen in the 2013 pre-Broadway performances of
The Bridges of Madison County as Carolyn, and she continued the role when the production moved to Broadway the following year. The show closed on May 18, 2014, after 137 performances. In 2014, Kinnunen auditioned for the role of Alyssa in a reading for
The Prom. She ultimately was cast as the lead character, Emma Nolan, and went on to perform the role in Atlanta in 2016, before the show moved to Broadway in 2018. For this performance, she was nominated for a
Tony Award for
Best Performance by a Leading Actress in a Musical. Kinnunen and co-star
Isabelle McCalla's kiss during their performance at the 2018
Macy's Thanksgiving Day Parade made national news as the first LGBT kiss in the parade's history. The production closed on August 11, 2019, after 23 previews and 309 regular performances. In May 2024, Kinnunen originated a lead role in the play
Choice by
Winnie Holzman at
McCarter Theatre Center in New Jersey. In December 2025, Kinnunen began starring as
Margaret Crane, inventor of the home pregnancy test, in an Off-Broadway production of
Predictor, a play by Jennifer Blackmer about Crane's life. == Personal life ==