Vaezi spent ten years at Freuds as a director of strategy and planning, creating campaigns for comparethemarket.com, Pepsi, Airbnb and Asda.
At Ogilvy he will work with the agency's creative teams developing a strategy and planning function across the EMEA region.
Stuart Smith, global CEO of Ogilvy Public Relations, said: "Serge has an outstanding track record and is exactly the type of strategic talent we need.
"Serge joins Ogilvy PR EAME at an exciting time. We are four years into a programme that has transformed our capabilities, our reputation and seen us extend into new geographies. I know he will add tremendous value to the work we do and raise expectations of the role of PR in an integrated environment."
Vaezi has previously worked at Cubo Group and DDB.