Judson has 20 years of experience in database management, most recently as head of the European Data Systems group at AOL.
His appointment is part of a wider restructure that sees Ol Janus promoted to the role of client services director, a new role at the agency.
Richard Greenhalgh, managing director of EHS Brann Discovery, said: "Delivering a first-class service to our ever-growing client list is at the forefront of our business.
"We will continue to drive this using Mark's expertise supported by Oliver."