Cohen will be based at the group's Canary Wharf offices and is delighted to join the company.
"This is an exciting role with masses of opportunities to enhance and evolve across the board," she said.
Ocean Media Group managing director James Brooks-Ward added: "Tanya has an impressive track record in the exhibition industry, with successful and high-profile exhibition launches to her credit."
One of Cohen's previous tasks was running the inaugural Square Meal Venues & Events exhibition at Old Billingsgate five years ago.
This is the second high-profile appointment made by Ocean Media in as many weeks. Andy Gibb, formerly group managing director of Opex Group, has been brought on board to head the group's Coventry office and leisure section.
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