Gittins joins the agency as a company director following a brief stint leading Edelman’s healthcare team.
His arrival re-establishes a partnership with Pearson, who joined Firstlight in 2011, after the pair co-founded Red Health at The Red Consultancy in 2007.
It also sees him team up once again with Firstlight founder Paul Davies, who headed up Red’s corporate team between 2006 and 2009.
Pearson, MD Healthcare, said: "It’s a really exciting time for us – brand new offices, a growing team of talented people like Paul and some significant new business wins to start the New Year with a bang."
Gittins left The Red Consultancy last summer to become group MD of the Edelman’s Health and BioScience practice, a role he quit shortly after.
A pharmacologist by background, he has also worked at Ruder Finn, MS&L and Red Door.