Platt then briefly attended Columbia University in New York, but it was only a matter of weeks before he dropped out to accept the role of Benji in the 2012 film comedy-musical Pitch Perfect. Focusing on the world of university a cappella competitions, the movie's hit cast album arrived via Universal
in September of 2012. Later the same year, Platt began a run as Elder Cunningham in the Chicago production of The Book of Mormon. He went on to make his Broadway debut in January 2014 in the same role, leaving it in January 2015. Pitch Perfect 2 followed later in 2015, as did a role in the Meryl Streep
comedy-drama Ricki and the Flash. He spent July and August of 2015 playing the title role in a Washington, D.C. production of Dear Evan Hansen, a stage musical he'd joined in the workshopping stages.
In December 2016, Benj Pasek
and Justin Paul
's Dear Evan Hanson opened on Broadway. About a high school senior whose social anxiety made it difficult for him to connect to others, the show became a box office hit and garnered nine Tony Award nominations. It won six, including Best Musical, Best Original Score, and Best Performance by a Leading Actor in a Musical for Platt. The original Broadway cast recording entered the Billboard 200 at number eight in February 2017, the highest debut for a cast recording since Camelot in 1961. Two months later, Platt was named one of the Time Magazine's 100 Most Influential People, and in September, he signed with Atlantic Records
as a singer/songwriter.
In March 2018, Platt collaborated with Lin-Manuel Miranda
on the benefit single "Found/Tonight," a mash-up of songs from Hamilton and Dear Evan Hanson. It was released by Atlantic
in conjunction with March for Our Lives, a protest march to promote gun reform following the mass shooting at a high school in Parkland, Florida a month earlier. It reached the top half of the Billboard Hot 100. ~ Marcy Donelson, Rovi