He joins from his role as digital strategist at Ogilvy PR London, where he worked for nearly two years.
Poulter will work with Euro RSCG Biss Lancaster MD Holly Ward across the agency's consumer and corporate clients including RBS, the Army, BAE Systems, Reckitt Benckiser and Huggies.
Ward said: 'Digital communications is at the heart of our business strategy.
'I am delighted to welcome James to our team. He is a pioneer in social media communications and we look forward to providing our clients with more comprehensive digital PR programmes.'