The agency is parting ways with Muller following the yoghurt-makers decision to return to a more conventional form of advertising, moving away from the agency's more radical strategy to engage new audiences.
TBWA\London launched Müller's £20m advertising campaign, 'Wunderful stuff', it's biggest ever, in October, which included cartoon characters from the 80s such as Yogi Bear and Mutley dancing in a street.
The agency will continue to work with Muller until a replacement agency is found.
Müller's marketing director Lee Rolston left the company last month after holding the role for just over a year. His departure was part of cuts to senior management and a shake-up of its UK business, which also saw the exit of the company's UK chief executive, Gharry Eccles.
In February Muller consolidated its advertising account into TBWA\London after a winner-takes-all pitch involving its other roster agency VCCP.
The agency has worked with Muller since 2004 after winning the UK account from Publicis.
Robert Harwood-Matthews, president at TBWA UK, said: "We had some brave clients and we all know we did something wunderful, no regrets."
Muller was unavailable for comment at the time of publishing.
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