Banham will report to Russell Ramsey, JWT London's executive creative director, and will be responsible for overseeing the agency's digital output.
Fernanda Romano, who previously oversaw digital creative at the agency, left earlier this year to take on the role of global creative director of digital experiential at Euro RSCG Worldwide.
Banham has worked at a number of major digital agencies in the past few years.
In 1999, he joined WCRS as its first interactive creative head, working on a high-profile campaign for Mini, while in 2001 his "superstitial" work for BMW won awards.
After leaving WCRS, Banham worked as the creative director at the digital agency itraffic and as the European executive creative director at Agency.com before joining AIS as its first executive creative director in September 2007. During his time at AIS, Banham was responsible for creating the "fill the indigO2" work for O2, which won a Cyber Lion at Cannes and saw the agency recognised as the most awarded digital agency of 2008 by the International Advertising Bureau.
Banham said: "I'm looking forward to working with Russell and to helping the agency expand its digital offering."
Last week, JWT London confirmed the appointment of Guy Hayward as its new chief executive.