He takes over from Paul Wheeler, who left the agency at the end of last year.
Broadbent has been tasked with overseeing the "continued growth" of the business across Manchester, Birmingham and Leeds.
He co-founded Brilliant Media in 2002 in Manchester which was then acquired by MediaCom in 2011. Broadbent began his career at J Walter Thompson in Manchester, and has also worked at McCann, Carat and Feather Brooksbank.
Simon Price, a board director and managing partner for the Leeds office, has been named managing director for the Leeds office.
Price joined Brilliant Media in 1999, and has also worked at MediaVest Manchester, which is now Carat, and Mark Nicholas Media.