O'Hara will play Babe Williams opposite Harry Connick, Jr., in the Kathleen Marshall-directed production, due to begin previews Jan. 19 at the American Airlines Theatre.
In Piazza, O'Hara plays Clara, a mature but mentally naive young woman who impetuously falls in love with a native Florentine boy while vacationing with her mother.
No replacement for O'Hara has been announced.
Tickets are now on sale to March 26. The show, a limited engagement at Lincoln Center Theater, was first extended to Jan. 1, 2006, after winning Tony Awards, including Best Score (Adam Guettel) and Best Actress in a Musical (Victoria Clark).
Craig Lucas penned the libretto, based on a 1960 novella by Elizabeth Spencer. Barlett Sher directed at the Vivian Beaumont Theatre.
Aaron Lazar and Chris Sarandon recently joined the cast as the new Naccerelli son and father. Aaron Lazar succeeded Matthew Morrison, who left the production to take a role in A Naked Girl on the Appian Way at the Roundabout Theatre Company. Lazar began work on Sept. 2. Sarandon followed on Sept. 13.
Piazza took home six Tony Awards on June 5. The show opened on April 18 after a month of previews.
The Light in the Piazza is a love story of a young American woman, Clara (O'Hara), who, while on holiday, falls for a young Italian man. When the young woman's mother (Victoria Clark) learns of the affair, she initially opposes it for unknown reasons. The musical is set in Florence and Rome in the summer of 1963.