He is on gardening leave with Brands2Life and departs the agency after two years. His clients included Cisco, Informa and NetSuite.
Starting in the role on 18 September, he replaces Simon Jones, who is moving to a central strategic post within the Bell Pottinger Group. ‘Simon will remain an executive director at Harvard and continue to work with his clients so there is no disruption,' said Bell Pottinger Group chairman Kevin Murray, to whom Cartwright will report.
‘Brands2Life was a great place to work, I am only leaving for positive reasons as this job was too big to ignore,' said Cartwright.
Before Brands2Life, Cartwright spent four years at Bite Communications as a board director. While he was there he founded and ran the agency's corporate practice, working with clients such as Deutshe Post.
Brands2Life co-founder Giles Fraser said he would not replace Cartwright, splitting his workload between senior management.
Harvard, which has 30 UK staff, has offices in London Germany and France, with clients including Vodafone and Sony PlayStation.