De Groose will continue to report to Robert Horler, the chief executive of Aegis Media UK.
Carat will not immediately fill the managing director role. Its former deputy managing director Richard Morris was recently appointed managing director of the sister Aegis agency Vizeum.
The senior management team will continue to report directly to De Groose. This team includes Richard Sexton, the chief operating officer; Matthew Hook, the chief strategy officer; and Jo Allan, the chief client officer.
In her new role, De Groose will increase her focus on the range of Carat’s businesses in the UK and work with other Aegis Media assets to improve the service to Carat clients.
De Groose, who joined Carat in September 2010, was previously the group managing partner at Naked Communications. Before that, she worked at Starcom and Stella Artois.
De Groose said: "I look forward to working with Carat’s management team to accelerate our reinvention to a media agency more closely aligned to clients’ business success."Follow @KatherinePLevy