According to David Jones, the global chief executive of Havas, the promotion acknowledges the work Robertson has done in delivering change at the UK agencies currently under her control.
He added that her brief was to export this model – which puts digital integration at the heart of agencies – to the global businesses.
Robertson will work alongside Andrew Benett. The pair will share the day-to-day running of the network, reporting to Jones.
Robertson said: "Building a new company from an existing one is the toughest gig in business – but that’s what we’re doing with digital inside all our units and all our disciplines."
She will remain the chairman of Havas Worldwide agencies in the UK.