Revill was Alan Johnson's special adviser when he was home secretary and health secretary. She previously worked for The Observer as Whitehall editor.
Revill joined GSK in January 2010 and was responsible for managing the news flow around products.
She pledged to help London Councils reach a wider audience 'both inside Westminster and across the capital'. She added: 'There has never been a more important time to communicate the value of the work carried out by London's boroughs.'