Banham left Agency.com last week along with its European planning director, James Clifton, as part of a restructure.
In his new role, Banham will assume creative responsibility for all of the agency's digital output.
He will report to the creative partner, Steve Stretton, and work alongside the creative director, Matt Morley-Brown, on integrated clients. These include O2, Skoda, Abbey, Dyson, Pioneer and Moet Hennessy.
Banham, who joined Agency.com in 2003 after a stint at WCRS, has picked up numerous awards, including a Campaign Digital gold for NSPCC in 2005 and a bronze Cannes Lion for Dulux in 2006.
He said: "There are some really strong brands here, some hugely talented people and an open-minded outlook built into the agency's structure."