His first acting work was at a theater operated by his aunt and uncle, where he debuted at age six as a Lost Boy in a production of Peter Pan.
[5][6] Gertner's subsequent roles have included William Barfee in the San Francisco and Boston productions of The 25th Annual Putnam County Spelling Bee.
[5]) Gertner played Warren in Ordinary Days with New York's Roundabout Theatre Company and performed on the original cast recording.
With Gad's departure, Gertner took over the role on Broadway, then co-starred with Gavin Creel in the production's first national tour, debuting in August 2012 in Denver.
[8][9] Gertner also co-starred with Creel in the London West End production of The Book of Mormon, which began previews on February 25, 2013.