In 1983, he debuted on Broadway, playing opposite Anthony Quinn in Zorba. McCarthy played Bob Freelander in Marvin Hamlisch and Howard Ashman’s ill-fated Smile, which opened on Broadway in November 1986. He played Terry in the original Broadway cast of Side Show in 1997, recorded for Sony Music. He is perhaps best known in the theater for his creation of Officer Lockstock in the Broadway production of Urinetown, which opened on Broadway in September 2001. From 1995 – 97, McCarthy played the “Beast” in the Broadway production of Beauty and the Beast . He played Dubhdara in the musical The Pirate Queen which opened on Broadway in April 2007. In 2008, 2009 and 2011, McCarthy played Billy Flynn in Chicago, the long-running Broadway revival. McCarthy created the role of Lola Cola in the premiere of the bluegrass musical, Southern Comfort which opened at the Off-Broadway Public Theater in March 2016.

McCarthy was chosen by Chuck Jones to be the voice of Michigan J. Frog in his 1994 Another Froggy Evening, a sequel to the original 1955 cartoon One Froggy Evening. McCarthy went on to voice Michigan J. Frog, “spokesphibian” for the WB Television Network.

In 2012, McCarthy played the title role in the stage version of How the Grinch Stole Christmas! at Madison Square Garden.

Danny And The Deep Blue Sea for the 29th St Project, NYC, The Glass Menagerie for the University of New Hampshire and Urinetown for the University of Oklahoma. Working with his brother, Jim McCarthy in 2016, he wrote, directed and edited Keepsake, a short film featuring his daughter, the actress Juliet Perrell McCarthy.

In February 2017 at the Off-Broadway 59E59 Theaters, McCarthy created the title character in Jeffrey Sweet’s Kunstler about the radical civil rights attorney, William Kunstler.” By popular demand, he went on to play the role in the Barrington Stage Company (Pittfield, Massachusetts) production, which opened in May 2017. (McCarthy is an associate artist at the Barrington Stage Company.)