Lee joins Blue Sheep from DQ Global, where he was vice-president of sales. He was previously head of business development for marketing services provider Occam.
Lee said: "I've been aware of Blue Sheep for a number of years and its prominence in the sector. I have a good understanding of what its customers think about the company and what their expectations are.
"I look forward to maximising the strength of our position and feel confident that we will experience an extended period of growth."
Although each of his positions were in the business-to-consumer sector, Blue Sheep is hoping Lee's B2C background will enable him to bring valuable industry and management experience to the B2B sector.
Blue Sheep's growth plans focus on its clients' needs, and the development of appropriate products.
Lee said: "Having released AIMP which helps marketers with their acquisition and retention activities, we need to move further and integrate the offline challenges with those that are occurring everyday in the online world."
John Wright and Iain Lovett, joint managing directors, will continue to take an active role in the company.