The account is estimated to be worth between $37m (£26m) and $50m (£35.2m). The account had previously handled by True North Communications' FCB San Francisco in the US and HHCL & Partners in the UK.
W&K will be tasked with creating advertising to run in all of Amazon's five major markets -- the US, UK, Japan, France and Germany.
Last December, the internet retailer ended its three-and-a-half-year relationship with FCB. At the time, the review shocked the US advertising market, where FCB's work had picked up a number of creative awards. One campaign used a male choir singing tunefully of the benefits reaped from using Amazon.com in its spots called "I spent two minutes", "tons of toys" and "just a few days to go". The campaign won a silver Clio at last year's Clio Awards.
FCB declined to pitch for the account, feeling that its past work for Amazon should speak for itself.
The review was called in an effort to position Amazon as an international online retail company.
Amazon and Wieden & Kennedy have declined to comment. The agency also numbers Nike, Coca-Cola and Walt Disney among its clients.
The review was conducted out of Amazon's Seattle, Washington headquarters.
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