[2] She also received Tony nominations for her performances in The Light in the Piazza (2005), The Pajama Game (2006), South Pacific (2008), Nice Work If You Can Get It (2012), The Bridges of Madison County (2014), Kiss Me, Kate (2019), and Days of Wine and Roses (2024).

In 2022, she returned to the Met, starring as Laura Brown in Kevin Puts' The Hours, a role she and co-stars Renee Fleming and Joyce DiDonato reprised for eight performance in May 2024.

For this performance, New York Times reviewer Ben Brantley wrote that O'Hara "rockets past the promising ingénue status she attained with Light in the Piazza".

concert staging of Sunday in the Park with George[15] and Eliza Doolittle in the New York Philharmonic's semi-staged production of My Fair Lady at Avery Fisher Hall.

[21] She played the role of Ellen in the film Sex and the City 2 (2010), and in 2011 she appeared in "Mercy", the first episode of the second season of the CBS show Blue Bloods.

[26] In 2012, at the New Year's Eve concert, "Celebrating Marvin Hamlisch", at Lincoln Center, she sang "At the Ballet", from A Chorus Line, along with Audra McDonald and Megan Hilty.

[27] In 2013, she played the lead character of Julie Jordan in the staged concert of Carousel presented by the New York Philharmonic at Avery Fisher Hall.

[29] Elyse Sommer, a CurtainUp.com reviewer, noted O'Hara's "superb vocal chops" and her "exquisite" duets with co-star Steven Pasquale.

[32] On December 31, 2014, O'Hara made her operatic debut at The Metropolitan Opera as Valencienne Zeta in Franz Lehár's The Merry Widow, alongside Renee Fleming in the title role of Hanna Glawari.

[34] She gave her debut solo concert at Carnegie Hall in October 2016[35] and guest-starred as the recurring character Dody Oliver on the fourth season of Masters of Sex.

[37] Jeremy Gerard of Deadline Hollywood called O'Hara's performance "luminous", writing: "O’Hara is impossibly beautiful, vocally and in conveying Fiona’s romantic determination and heartbreak.

[44][45] In a 2022 interview with Theatermania, she discussed working on three projects at once: HBO's costume drama The Gilded Age, from Downton Abbey creator Julian Fellowes; a new season of The Accidental Wolf, in a role that earned her a 2018 Emmy nomination, as a woman who becomes embroiled in a scandal after receiving a phone call from a stranger being murdered; and a role as Laura Brown in the operatic adaptation of Michael Cunningham's novel The Hours.

"[46] In May 2023, O'Hara originated the role of Kirsten Arnesen in the musical adaptation of Days of Wine and Roses Off-Broadway at the Linda Gross Theater.

[47] Upon the show's January 2024 opening, a review in New York magazine noted: "O’Hara sings all but four of the play’s songs, and her voice is the kind of instrument that sends people scrabbling for metaphors.