A qualified lawyer, Costillas joins Weber Shandwick Brussels form her role as director of public policy at Citigate Dewe Rogerson.
She replaces Chris Hierholzer, who has joined Hanover, Brussels.
Colin Byrne, CEO Weber Shandwick Europe, said: ‘Our Brussels practice is one of our global public affairs hubs. We're thrilled to announce Ana's appointment to the head of public affairs in Brussels, which marks a significant milestone in our efforts to expand and strengthen our public affairs practice internationally.'
Paul Baeyaert, managing director, Weber Shandwick Belgium, claimed: ‘This appointment sets us up to provide current and prospective clients with the most effective strategic, integrated public affairs-public relations campaigning and counsel in Brussels that money can buy.'