[3] Her theatre roles include Tuptim in the 2015 Broadway revival of The King and I and MwE in Ars Nova's off-Broadway musical KPOP.

[14] During her sophomore year in high school, at age 15, Park was diagnosed with acute myeloid leukemia and was hospitalized for eight months.

[10][15] Park was a recipient of a "wish" from the Make-A-Wish Foundation for which she and her family went to New York City and saw the Broadway productions of A Chorus Line, The Lion King, Spring Awakening, and Wicked.

She spent the following two summers performing in Pittsburgh Civic Light Opera's Benedum Center production of Miss Saigon, with which she earned her Equity card.

[21] From October 2014 to January 2015, Park portrayed Gabrielle in the original U.S. national touring company of Rodgers + Hammerstein's Cinderella.

[21][22] Park returned to Broadway on April 16, 2015, in her first leading role as Tuptim in the 2015 revival of The King and I at the Vivian Beaumont Theater and remained with the production until its closing on June 26, 2016.

[24] In February 2017, she appeared in the Broadway revival of Sunday in the Park with George as Celeste #1 and Theresa alongside Jake Gyllenhaal, Annaleigh Ashford, and Ruthie Ann Miles.

[28][29][30] Park left the production in October 2017 due to her beginning rehearsals for the Mean Girls out-of-town tryout and was replaced by Marina Kondo.

[32][33][34] The show had its world premiere as an out-of-town tryout at the National Theatre in Washington, D.C., from October 31, 2017, to December 3, 2017, in which Park originated the role of Gretchen Wieners.

[34][35] The musical, which is based on the film of the same name, began previews on March 12, 2018, and officially opened on Broadway on April 8, 2018, at the August Wilson Theatre in New York City.

[38] In June 2019, it was announced that Park would headline a "revamped" production of Thoroughly Modern Millie from May 6–10, 2020, for New York City Center Encores!.

[65] During her undergraduate years, Park was involved with the Prison Creative Arts Project, an organization that engages "those impacted by the justice system into artistic collaboration" with University of Michigan students for "mutual learning and growth through theatre, dance, visual art, creative writing, slam poetry, and music" in Ann Arbor, Michigan.

[69][70] In August 2018 Park participated in Covenant House's Stage & Screen Sleep Out along with Mean Girls co-stars Kyle Selig and Curtis Holland, and together they raised over $14,000 for the organization which provides shelter, food, and crisis care for the homeless and runaway youth.

[72][73] During the COVID-19 pandemic, Park set up a second Instagram account from which she began offering ten-minute one-on-one lessons and daily question-and-answer sessions via Zoom in exchange for donations to the Actors Fund.

[76] In late December 2023, Park was hospitalized due to life-threatening critical septic shock while on vacation in the Republic of Maldives.