Theater During the summer of 2008, Fahy attended open calls and was cast as the standby for
Jennifer Damiano as Natalie Goodman in
Arena Stage's production of
Next to Normal in late 2008. She remained with the cast during its transfer to the
Booth Theatre on Broadway, which began previews on March 27, 2009. On July 19, 2010, after Damiano departed the cast to prepare for the Broadway musical
Spider-Man: Turn Off the Dark the day before, Fahy took over as the principal actor for Natalie along with
Marin Mazzie as mother Diana and
Jason Danieley as father Dan.
MacKenzie Mauzy replaced her as the standby for Natalie. Fahy played the role on Broadway until its closing on January 16, 2011. In December 2010, it was announced that Fahy had been cast in readings of a stage adaptation based upon the 1992 Disney cult classic
Newsies.
Paper Mill Playhouse took on the musical for its 2011–12 season, with the production running from September 15 to October 16, 2011, though Fahy did not participate in that production. She has also recorded demos for composers' works, such as
Bree Lowdermilk and
Kait Kerrigan's
The Unauthorized Autobiography of Samantha Brown in 2009, and continues to perform in concert revues as the title character as recently as March 1, 2011. In May 2011, Fahy briefly reprised her role as Natalie Goodman in the first national tour of
Next to Normal in the first week of the St. Paul, Minnesota stop. Emma Hunton, who had been cast in the tour, took a leave of absence to complete a workshop in New York City. Fahy joined the rest of the principal tour cast for her stint:
Alice Ripley as Diana, Asa Somers as Dan, Jeremy Kushnier as Dr. Madden, and Preston Sadleir as Henry. In July 2011, it was announced that Fahy had been cast in
The Unauthorized Autobiography of Samantha Brown at
Goodspeed Opera House. She reprised her role as the title character when performances began August 4, 2011, and continued through August 28, 2011. In January 2015, Fahy participated in a production of
We Are The Tigers at
Feinstein's/54 Below, singing as Riley Williams. In fall 2015, Fahy starred
Off-Broadway in
Lost Girls at
MCC Theater playing the role Penny. In winter 2017, Fahy starred in
Penelope Skinner's play
Linda at
Manhattan Theatre Club Off-Broadway, playing a rock singer.
Television and film Fahy first appeared on ABC's
One Life to Live in February 2010 as college student Hannah O'Connor. She has described her character in these terms: "stalked an ex-boyfriend; overdosed on painkillers; has a fixation on a coed; witnessed a crime." The role ended in November 2010, with Fahy appearing as Hannah in two subsequent episodes in January 2012. Other television credits include a guest appearance on the series
Gossip Girl as Devyn. The following year, Fahy appeared in the miniseries
Political Animals as ambitious blogger Georgia, and guest starred on
Necessary Roughness as Olivia DiFlorio, tutor-turned-girlfriend of the main character's son. In 2016, Fahy was cast as Sutton Brady in the
Freeform drama series
The Bold Type, which premiered on June 20, 2017. She has won praise for her performance in this role, with one reviewer noting that "Fahy, giving one of TV's most charming and underrated performances, continues to define the show's fizzy, occasionally bawdy comic streak with exquisite timing and a particular aptitude for punchlines that hurt just a little bit". In November 2020, she was cast in a co-starring role in the drama film
The Unbreakable Boy. In February 2022, Fahy was cast in a starring role playing Daphne Sullivan, a woman vacationing with her husband, in the
second season of the
HBO drama anthology series The White Lotus. She had auditioned for
Alexandra Daddario's role in the first season of
The White Lotus. Her performance in the second season was praised, with
Vanity Fair proclaiming that Fahy would be the "breakout" star of the series' second season. Adrian Horton of
The Guardian also lauded Fahy and declared that it was "Fahy's performance that elevates her [character] from dimensional to thrillingly unpredictable and inscrutable." Along with her castmates, in February 2023, Fahy garnered an
SAG Award for Outstanding Performance by an Ensemble in a Drama Series. She also received a nomination for
Outstanding Supporting Actress in a Drama Series at the
75th Primetime Emmy Awards for her performance. In 2025, Fahy starred as the lead in the
thriller film
Drop. Fahy earned praise for her performance as a survivor of domestic violence, with
Empire proclaiming that "her groundedness is the antidote to the film’s silliness". In November 2025, it was announced that Fahy will star in the thriller film
Banquet, directed by
Galder Gaztelu-Urrutia, alongside
Alfie Williams,
Corey Mylchreest, and
Finbar Lynch, and will be produced by
David Yates. ==Personal life==