Lawrence was previously a digital account director at the Aegis-owned media agency, and, before that, was a digital planner and buyer for Oscar/LBi.
He will join the MediaCom investment team and report to Rhys McLachlan, the head of broadcast implementation at the WPP agency.
He leaves Carat at a time of transition in the agency’s digital offering.
In June, parent company Aegis scrapped the Diffiniti digital agency brand in the UK, as part of a global rollout of its US-based iProspect search specialist.
Recent departures from Diffiniti include Paul Vassallo, who was head of digital trading and headed the agency’s Sky account. Vassallo left the agency to join Havas Media's Media Contacts as head of digital trading and head of display.
In May, James Harris, the Diffiniti deputy managing director, also left the agency to join Universal McCann as head of digital for the EMEA region.