Dreyfuss earned a BFA in musical theatre from the Boston Conservatory.[2] Dreyfuss was cast in the ensemble of the Broadway revival of Hair, then served as stand-by and later was a replacement for the main character of Girl in the musical Once.[3]
Dreyfuss originated the role of Zoe Murphy, the love interest of the title character, Evan Hansen, in the Broadway musical Dear Evan Hansen after previously playing the role in both the Arena Stage and Second Stage Theatre productions.[4] On July 12, 2018 it was announced that Dreyfuss would leave Dear Evan Hansen, with her last show being July 15, 2018.[5] On July 16, 2018 Dreyfuss was announced as a series regular on Ryan Murphy's Netflix series The Politician, with her Dear Evan Hansen co-Star, Ben Platt.[6] On July 26, 2018, Dreyfuss released her debut single "Be Great" under the stage name Loladre.