Roberts started work this week as UK MD and takes charge of the day-to-day running of the agency's 60-strong Canary Wharf office.
The appointment comes as part of an ongoing agency restructure, said Ogilvy EMEA chief executive Martin Liptrot.
Liptrot joined Ogilvy this January from a US-based role at FedEx. He has known Roberts, a Brit, since his time at FedEx, when he worked with Ketchum.
Roberts trained as a lawyer in the UK before moving to CNN in the US. He joined Ketchum in Atlanta ten years ago. He has also previously worked in the Far East and New York for Ketchum.
Roberts's role at Ogilvy is newly created. He is aiming to ‘lead the senior management team' in growing the business.