Ben Platt, encircled by the cast of “Dear Evan Hansen.” (Matthew Murphy)

Ben Platt, who more than three years ago spoke the words and sang the music of “Dear Evan Hansen” for the first time, going on to win the Tony Award in June for best actor in a musical, will leave the celebrated musical in the fall, the show’s producers announced Monday.

His last performance at Broadway’s Music Box Theatre, where the show collected six Tonys, will be on Sunday, Nov. 19, according to the production and Platt, who confirmed his departure on Twitter. “2 readings, 2 workshops, 3 productions and almost 4 years- hard to fathom that’s it’s nearly time to say goodbye to Evan and my DEH family,” Platt said.

In a portrayal that will be long remembered as an extraordinary Broadway milestone, Platt has played the role of Evan — a lonely and anxiety-ridden teenager who fabricates a story that boosts his celebrity and leads to anguish — in every incarnation of the show. That includes the world-premiere stint of the musical by Benj Pasek, Justin Paul and Steven Levenson at Arena Stage in Washington and at off-Broadway’s Second Stage Theater. By the time he leaves in mid-November, he will have played the vocally and emotionally demanding role on Broadway for just over a year.

His contribution, under Michael Greif’s direction, has widely been seen as central to the musical’s runaway success. It plays every week to standing-room-only audiences at the Music Box, has a weekly box-office take of more than $1.5 million and is already turning a profit for its investors. The huge question now is how the show fares without him. Platt had a solid track record before “Evan Hansen,” as a result of his work as a replacement for Josh Gad in “The Book of Mormon” and his appearances in the “Pitch Perfect” movies. But he leaves “Dear Evan Hansen” a bona fide star. NBC’s reprise of “Will and Grace” has already announced that he will appear as a guest on its Oct. 5 episode.

Whether other original cast members of “Dear Evan Hansen” will be leaving — they include Rachel Bay Jones, another Tony winner; Tony nominee Mike Faist; Michael Park; Jennifer Laura Thompson; Laura Dreyfuss; Kristolyn Lloyd; and Will Roland — has not been disclosed. Representatives of “Dear Evan Hansen” said Monday that casting news will be forthcoming in the near future.