Gelber represented the 106th district in the Florida House of Representatives from 2000 to 2008, also serving as House Minority Leader in his last term. He then served in the Florida Senate, representing the 35th district from 2008 to 2010. He ran for Attorney General of Florida in 2010, losing the general election to Republican Pam Bondi. In 2012, he co-founded the law firm of Gelber Schachter & Greenberg, P.A. along with Adam Schachter and Gerald Greenberg. The firm handles complex civil litigation and white-collar criminal defense cases in Florida and across the country.