Kai Gait rejoins in a newly created role as digital marketing director of the pharma division.
The move comes after ten months working as Roche's global digital marketing lead, before which he was digital commerce marketing manager at GSK.
A GSK spokesman said: 'Kai's new role will help to develop digital channel materials and services, built on robust customer insight. He will also be building our understanding of how technology can support behavioural change in the healthcare environment.'
Gait said he was interested in integrating social media across GSK's pharma, consumer and corporate divisions, which currently have separate teams of digital specialists.
Gait said: 'I use customer psychology to try to understand why people interact in the way they do. I believe that is often lacking in an organisation.'
One of Gait's first projects will focus on improving customer engagement and impact of the public.gsk.co.uk website, which provides information for healthcare professionals and members of the public on GSK products.
Speaking at PRWeek's Pharma Communications conference last month, Gait was critical of drug companies that fail to ensure social media projects are resourced for the long term with a dedicated manager, or fail to put the user first by consisting entirely of corporate content.
In January, PRWeek revealed that GSK was launching a review of its multi-million-pound UK PR roster.