In 2021, Faist starred in the series Panic and had his first major film part as Riff, the leader of the Jets, in Steven Spielberg's West Side Story, for which he received a nomination for the BAFTA Award for Best Actor in a Supporting Role.

[8] On his first job as a professional actor in the play White Christmas, he was collecting food stamps, earning $150 per week, and living in the back of a McDonald's parking lot.

[6] Faist began his acting career in 2011, originating the role of Morris Delancey, a bully and publisher Joseph Pulitzer's henchman, in the regional premiere of Newsies at the Paper Mill Playhouse.

"You have to really make sure you're warmed up vocally and physically and you're mentally prepared," Faist said of the demands of his dual role, but added, "It's not hard to have fun in Newsies, about the uprising of children, a new generation coming in to take over the old.

[14] In 2015, he appeared as Skip in the short film Yellow, a psychiatric ward patient in Touched with Fire, and Gordie Joiner in The Grief of Others which received critical and generally positive reviews.

[15] He was also cast in an unaired pilot of the series Eye Candy as Olsen and co-starred as tutor Aleksei Belyaev opposite Peter Dinklage in an Off-Broadway production of A Month in the Country.

"[8][20] Along with cast members Ben Levi Ross and Mallory Bechtel, Faist lent his voice for the audiobook version of Val Emmich's Dear Evan Hansen: The Novel, a book adaptation of the musical released in October 2018.

In October 2017, he taught Improv and acting exercises in a Broadway Musical Theatre Workshop and also held a Master Class for audition technique and song interpretation.

[4] In 2018, he appeared in an episode of Deception and starred in the Second Stage Theater production of Days of Rage as Spence, a conflicted and passionate young man torn between causes and women.

[27] The New York Times spoke of Faist, describing him as tall and lanky, making quite a striking figure in the series, "With a slender charisma and a bone structure that seems to have been sculpted with a scythe, the actor could easily have embarked on Panic.

[31] Later that year, he had his first major movie role in Steven Spielberg's film adaptation of West Side Story as Riff, Tony's best friend and leader of the Jets gang.

[34] The Washington Post regards his magnetic performance as West Side Story's "stand-out" as its chief film critic Ann Hornaday wrote "The revelation in this production, however, is Mike Faist, who is not only a gifted singer and dancer, but plays Jets gang leader Riff with just the right mix of spiky resentment, hair-trigger anger and loose-limbed grace.".

[35] On his collaboration with Faist, screenwriter Tony Kushner says, "He really wants to think about economics, politics, psychology, and psychotechnology, and he feeds himself with a kind of acuity and precision that I think is the mark of a great actor.

[38] Faist made his West End debut in the stage adaptation of Brokeback Mountain as Jack Twist, opposite Lucas Hedges as Ennis Del Mar, in May 2023.

[43] Faist starred with Zendaya and Josh O'Connor in Luca Guadagnino's romantic drama Challengers as Art, a famed tennis player facing his rival.