In 2006, Ulman ran for county executive against Republican Party opponent, Christopher Merdon, and Independent candidate, C. Stephen Wallis. A major theme of Ulman's campaign was his claim he played a role in preventing the closure of Columbia’s Merriweather Post Pavilion. Ulman won in the general election with 52% of the vote and was sworn in on December 4, 2006 at age 32, becoming the youngest person in Maryland to be elected as county executive. During his tenure as county executive, Ulman served as chairman of the Baltimore Regional Transportation Board and the Baltimore Metropolitan Council. He was also on the board of directors of the Maryland Association of Counties and County Executives of America.