James will report into David Pullan, head of client services at Isobar; his appointment completes a series of senior management changes at the digital outfit.
Isobar has also promoted Fiona Lloyd, client services director in Aegis agency Carat's global management team, to the role of vice-president of programme management. Simon Tait has been promoted to new business director from Aegis Media division ACT, where he was director of digital.
Pullan said the appointments were part of Isobar's policy of putting "digital thinking at the top of clients' agendas" and claimed that Isobar now has a world-class team in place.
James, the most high profile of the new appointments, joined Bacardi Global Brands in 2006 as head of digital to lead the drinks firm's digital marketing strategy for brands including Bombay Sapphire, Grey Goose Vodka and Martini.
He appointed digital creative agency glue London to Bacardi's global digital roster in March 2008 and commissioned the agency to launch a global digital-only campaign celebrating the brand's history in May.
Isobar last month boosted its client management team by hiring Niku Banaie as vice president of strategy and innovation from comms planning agency Naked Communications where he was UK managing partner.