During the pitch process, run through ISBA, ad agencies were partnered with media agencies to offer Ladbrokes an integrated solution.
Walker was appointed despite being paired with its sister agency M&C Saatchi, which was the incumbent on Ladbrokes' ad account but lost to SapientNitro, which was partnered by PHD.
The agency appointments follow Ladbrokes' announcement that it plans to invest £50 million in revamping its brand over the next two years, in order to help tackle falling profits.
The bookmaker's recent advertising has used the former footballers Chris Kamara and Ian Wright and the strapline: "Got the feeling? Get to Ladbrokes."