James, a former managing director of Manning Gottlieb OMD and Mediaedge:cia, and the head of Naked Ambition, the Naked Communications/Grey London venture, will lead a team of 70.
They will be working on internationally aligned accounts such as PepsiCo, Elizabeth Arden, Sony and Vodafone.
In addition, Damian Winstanley and Oliver Stroh have been promoted to joint dep-uty managing directors.
The move is part of OMD's attempt to strengthen its service on international and regional business. James rejoined OMD in 2004 to head the Nissan business across Europe.
After leaving MG OMD, in 2002, he launched his own content agency, before returning to mainstream media.
James said: "International is where the future growth of our business lies, and, in turn, OMD International in London must continue to help spearhead and contribute to the development of our global proposition."