Thousands of sports fans cheered and waved flags at the athletes, who included Zara Phillips, Victoria Pendleton, Mo Farah and Chris Hoy.
Cyclist Sir Chris, who won two gold medals during London 2012, said: "This isn't really for us, this is for [the public] because they've made the Games.
"They've made the atmosphere, they've supported the athletes, not just in the venues, but through the streets, and the pubs, the public venues - it's been incredible. So it's our chance to give them a wave and a thank you for all the support they've given us."
In total About 800 athletes - more than 90% of Britain's medallists - travelled on 21 open-top floats through the capital.