The agency will be responsible for branding across the Games' entire communication strategy, including Olympic venues and all marketing material.
Wolff Olins emerged victorious from a shortlist, believed to have comprised five agencies, following a three-month pitch process handled by the AAR.
It is thought that the brand consultancy's previous experience of working with the Athens 2004 Olympics organising committee was key to it winning the multimillion-pound London 2012 business.
The London 2012 Organising Committee (LOCOG) has also begun the search for a commercial director, setting an application deadline of 4 April.
The successful candidate will be responsible for generating £2bn in revenues over the next six years from marketing, sponsorship, merchandising and ticketing programmes.
The recruitment process is being handled by Odgers Ray & Berndtson. The successful applicant is expected to be in place by the summer, reporting to chief executive Paul Deighton, who takes up his post in April.