He will handle a variety of global and local accounts and report to Gerry Human, the chief creative officer. Dennis Lewis is the other creative partner.
Cartmell joins from Karmarama, where he has been a creative director since 2012, working on brands including Costa, B&Q, Iceland and Honda. Before that, he was part of The Red Brick Road’s founding team.
Cartmell has also worked at Lowe and Partners, Ammirati Puris Lintas, DDB Needham and McCann Erickson in Asia.
His most-awarded work is "pilot" for Stella Artois, which he created while at Lowe.
Cartmell said: "I remember being given a copy of Ogilvy On Advertising on my first day as a junior copywriter. Since then, I’ve always admired the agency’s ability to create powerful, award-winning work for big brands.
"To be joining Ogilvy London as it is about to start a new era at Sea Containers House on the South Bank is a real honour and hugely exciting."