A PR stunt for Jackpot Joy, the 50-foot inflatable duck began its journey at 8.30am near The O2 before making its way to Canary Wharf at around 9am and Tower Bridge at 10am.
It then reached London Bridge before starting its journey back the other way.
Bingo company Jackpot Joy hopes the rubber duck will inspire people to have more fun and laughs, as part of their new Facebook FUNdation marketing campaign.
Patron of FUNdation and EastEnders star Barbara Windsor said: "We thought a giant rubber duck floating down the River Thames was a great way to kick the FUNdation off, and it definitely raised a smile and a chuckle from everyone who saw it.
"After the Queen's Diamond Jubilee Pageant, the floating Olympic rings and David Beckham jetting into the Olympic opening ceremony, the Thames really has seen it all this year."
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