The move completes a raft of management changes at the UK offices of the Havas-owned network.
In her new role, Robertson will be charged with driving growth and increasing collaboration between the various companies in the UK group. These include Euro RSCG London, EHS Brann, Euro RSCG 4D (the group's digital arm), the public relations company Biss Lancaster, and Conran Design. She will remain the global account manager on the international Reckitt Benckiser business.
Robertson will report to the Euro RSCG Worldwide chief executive, David Jones. Her post at RSCG Fuel, which she set up to service Jaguar and Volvo, has yet to be filled.
Jones said: "Kate has enormous amounts of energy and is incredibly good at driving growth and delivering new business. She's also brilliant at team-building and getting people to work together."
Robertson, 50, joined Euro RSCG in 2003 after a stint as the chief marketing officer at D'Arcy Group EMEA.