After college, Foa landed his first major role, starring as Jesus in the off-Broadway revival of Godspell. He went on to act in many other productions, and made his Broadway debut in 2001 in the original cast of Mamma Mia! After six months with the show, Foa left to accept a three-month job at TheatreWorks in Palo Alto, California, where he created the lead role in a musical called Kept with music by Henry Kreiger and lyrics by Bill Russell.
While still performing as Cupid, Foa began the audition process for Broadway's Avenue Q. After two months, five auditions, and a lot of puppet practice, he became an understudy to the roles of Princeton/Rod in December 2003. After the show had run for about a year, Foa was promoted and began to perform the lead role on February 1, 2005. He continued in the lead role for a year and a half. While performing in Avenue Q, Foa was offered the role of Leaf Coneybear in the Broadway musical The 25th Annual Putnam County Spelling Bee. For two weeks he rehearsed for Spelling Bee during the day and performed Avenue Q in the evening. His stint as Leaf Coneybear lasted from July 11, 2006 until April 15, 2007.
He played his last performance as Frederic in Pirates! an updated version of The Pirates of Penzance, on July 8, 2007, again, at the Paper Mill Playhouse. He played Karel in The Lady In Question, a play by and starring Charles Busch from August 14 through September 2, 2007.
In May 2008, he played Jordy in a workshop of Giant, a new musical with music and lyrics by Michael John LaChiusa and book by Sybille Pearson, based on the Edna Ferber novel and the movie with Rock Hudson, Elizabeth Taylor, and James Dean.
In March 2009, Foa was cast in a recurring role on the CBS series NCIS: Los Angeles as Eric Beale, a technical operator in the Office of Special Projects. In January 2010, the role was upgraded to series regular.
Foa appeared in the musical revue For the Record: John Hughes at Show at Barre in Los Angeles, which ran from November 2010 to January 2011 and also stars Tracie Thoms, Von Smith, and Ty Taylor.
