Lee is currently a director focused on health at the agency Luther Pendragon, which she joined in 2013 having spent two years as CEO of Ketchum in the UK.
Lee will work closely with James Warren, UK and EMEA head of digital, to change the way clients engage with health professionals and consumers through social media.
She said: "The healthcare team at MSLGroup has the potential to be unique within the industry. The agency’s strong heritage in corporate, consumer and health communications, combined with its deep digital skills, is incredibly compelling.
"Offering clients a truly integrated service that has healthcare expertise at its core is especially important when it comes to health and pharma organisations seeking ways to engage through digital and social channels in an ethical and sensitive way."