Marcoms recruitment firm Pathfinders handed Bell the award last week at the group's annual event, held this year at BAFTA in London.
Bell beat four other nominees to win the award: Citigate Technology chairman Suzy Frith; Burger King internal comms director Kai Boshmann; The Economist international circulation director Christopher Collins and Abbot Mead Vickers BBDO deputy MD Farah Razman.
Bell was nominated by Shine director Erika Hendrick, who joined the agency two-and-a-half-years ago as an account director and was promoted to director in January. She was named Best Young Professional at last year's PRCA Frontline Awards.
The Media Boss of the Year panel of judges included last year's winner, Ogilvy & Mather worldwide client services director Neil Hamann and Biss Lancaster Euro RSCG chairman and 2000 Media Boss Graham Lancaster.
The panel said of Bell: '(She) has the edge when it comes to her management style and she scored highest on personal warmth, integrity of purpose and emotional intelligence.'