O'Leary was previously the international creative director of CLM BBDO in Paris, which he joined in 1995 as a senior art director. Before that, he spent four years at Ogilvy & Mather Paris, working on accounts including IBM, Disneyland Paris and American Express.
After a three-year spell as a copywriter at CLM, O'Leary took over as the international creative director in 2003.
He has worked across a wide range of brands including Apple, PepsiCo, Wrigley and Gillette. His work for France Telecom was awarded a silver Lion at Cannes.