He also founded his own musical theater company in middle school, Zneefrock Productions, as part of his bar mitzvah project to raise money for autism research.

After taking time off of high school to star in Dear Evan Hansen, Feldman initially decided to attend Harvard University in the fall of 2020, but he deferred his enrollment a year to 2021 because of the COVID-19 pandemic.

[1] His performance was lauded,[9] with Sarah Bahr in the New York Times writing, "Andrew Barth Feldman made me forget where I was, who I was, that I was anything other than part of the world onstage...I'm pretty sure I didn't draw breath the entire first act.

Feldman began a fundraiser for the Actor's Fund called Broadway Jackbox in March 2020, alongside former Dear Evan Hansen co-star Alex Boniello.

[12] On December 28, 2020, it was announced that Feldman would star as Linguini in a benefit concert presentation of Ratatouille the Musical, an internet meme that originated on TikTok, inspired by the 2007 Disney/Pixar film.

[13] His performance was celebrated, with Jesse Green writing in The New York Times that Feldman "seems to have animated his face to match Pixar's version: He's instantly adorable while looking like he still might gnaw your toe.

[17][18] He starred opposite Jennifer Lawrence in No Hard Feelings in June 2023 as Percy, a soon-to-be college student who is also socially clueless.

On September 23, 2022, Feldman and Joe Serafini released "In My Head", a duet written by songwriters Daniel Mertzlufft and Jacob Ryan Smith about the budding romance between two young men.