Smith, who joins Tamar's management team and will report to chief executive Tanya Goodin, is joined at the agency by new recruits Philip Cross, Grant Baxter and Ruth Zohrer.
Cross was previously at Steak Digital and at Tamar will take up the role of senior search campaign manager; Baxter joins from Adfero and becomes search campaign manager; while Zohrer adds to Tamar’s commercial team in the guise of business development manager.
Smith will focus on building the agency's insight and analytics services, which are designed to strengthen clients' digital marketing strategies with a range of research and analytics tools.
He previously co-founded PPC and SEO specialist Guru Web Consultancy in 2003, but will now relinquish management of the agency. He held posts at Tesco and e-Envoy.
Goodin said: "We needed someone with the vision, experience and track record of delivering insightful strategies across a range of industry sectors to lead our team.
"Colin answered this remit perfectly, and he's already made his mark on the agency and our campaigns across the board."