Hobsbawm is charged with overseeing Agency.com's international marketing strategy and will continue to be based in the London office. His appointment comes a month after sister interactive agency itraffic was folded into Agency.com.
Hobsbawm was the founder of Online Magic in 1995, which was bought by Omnicom Group and merged with Agency.com in 1997.
Don Scales, chief executive of Agency.com, said: "Andy has been a hugely influential force in both Agency.com and the industry since we began almost 10 years ago. His passion and dedication to all things interactive will continue to shape the future of our business and grow the company further."
Agency.com's clients include British Airways, eBay, Hewlett-Packard and T-Mobile.
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