The former Abbott Mead Vickers BBDO chief executive will take over as the chief executive of BBDO at the beginning of next month in succession to Allan Rosenshine, 65.
At 43, Robertson becomes the youngest chief executive of BBDO in its 113-year history. He takes responsibility for 290 offices in 77 countries.
Rosenshine, a one-time copywriter who joined the network in 1965, will remain as the chairman of BBDO Worldwide on a full-time basis for the next two years.
Robertson adds the global chief executive's role to his current title of BBDO worldwide president. He will give up his role as the head of the network's North American operations.
Robertson was drafted in to New York in early 2001 in a move that marked him out as the leading candidate to take over Rosenshine's mantle.
"The choice of Andrew should not surprise anyone," Rosenshine said. "It was clear since he came to New York he was my potential successor."
He added: "In the three years he has been here, he has shown the talent, the intelligence, the energy and the sensitivity to our culture and our clients to make him the right person to lead us."
Robertson owes his break into BBDO to Michael Baulk, the AMV chairman and his long-time friend and mentor.
Baulk, then the managing director of Ogilvy & Mather, gave Robertson his first job as a media planner in 1982. Robertson later joined J. Walter Thompson but was reunited with Baulk in 1995 when he joined him at AMV as the managing director.
Robertson's departure for the US disrupted the management succession at AMV, although his pragmatic style was said by some to be counter to the agency's culture.