Guettel attended Phillips Exeter Academy, School Year Abroad (SYA France) and Interlochen Center for the Arts.
[4] While at Yale, Guettel took time off from school to work as John Mauceri's assistant and the DX7 consultant on the broadway musical Song and Dance.
In The New York Times review of the show, critic Ben Brantley noted "Mr. Guettel establishes himself as a young composer of strength and sophistication, weaving strands from the Americana of Copland and the uneasy dissonance of Sondheim".
Later, Guettel would say that it was his time working on Floyd which made him certain that he would spend his life writing music for the theatre.
[4] The second project he developed with Landau and Sperling was a song cycle titled Saturn Returns (recorded as Myths and Hymns).
"And we realized in some ways that the hymns are who we would have ourselves be, and the myths are basically who we are, and that they can kind of antiphonally talk to each other", said Guettel, in a 2021 New York Times interview on the online MasterVoices production of the piece.
His major influences include Igor Stravinsky, Maurice Ravel, Claude Debussy, Benjamin Britten, and Stevie Wonder.
He spent much of the period from 2005 to 2007 working on a musical adaptation of The Princess Bride with original screenwriter William Goldman.
An orchestral suite from the score was performed at the Hollywood Bowl in November 2006, and Lincoln Center conducted a workshop of Bride in January 2007.
The project was abandoned when Goldman reportedly demanded 75 percent of the author's share, even though Guettel was writing both the music and the lyrics.
In summer 2007, Guettel composed incidental music for a production of Anton Chekhov's play Uncle Vanya at the Intiman Playhouse in Seattle, Washington.
[15][16] Shortly after Days of Wine and Roses closed on Broadway, it was announced that Guettel's musical, Millions would make its world premiere at the Alliance Theater.
[17] In June 2024, it was announced that Floyd Collins would come to Broadway as a part of Lincoln Center Theater's 40th Anniversary season.
Since 1995, he has taught masterclasses and seminars in musical theatre performance and songwriting, considering this to be an important complement to his work as a composer.
[27] In an interview, Guettel stated a portion of his influences that included I. M. Pei, Louis Kahn, Vincent Scully, Jane Jacobs, Igor Stravinsky, Stevie Wonder, Adam de la Halle, Harry Nilsson, Ruth Bader Ginsburg, Björk, Erich Wolfgang Korngold, Benjamin Britten, William Inge, Stephen Sondheim, Jody Williams, and Marvin Gaye.