Affleck will join in August from Profero, where he is the group account director on the Channel 4 account. Before joining Profero last October, he was the head of digital strategy at ZenithOptimedia, and previously worked at its sister agency Zed Media.
At Vizeum, Affleck will lead the agency's approach to digital media across all clients. He will also work closely with Matthew Hook, the head of planning, to deliver on Vizeum's integrated strategy.
The appointment adds clout to Vizeum's offering after its managing partner, Ben Wood, left to join the online ad network TradeDoubler.
Grant Millar, the joint managing director of Vizeum, said: "Patrick will be a great asset to our clients and to our business as we continue to invest in digital capability. A third of our staff are digital specialists, working in complete integration with our broader media skillsets."
Affleck said: "Vizeum is going further than any other media agency to harness the digitalisation of all media in the interests of its clients."