The Jamaican sprinter and Olympic gold medallist dresses as billionaire Branson in the TV ad to promote Virgin Media's pledge to double the broadband speeds of 4.1m customers for no extra charge.
In the campaign, which launches tomorrow during ITV1's Take Me Out, Bolt becomes the 'beard', donning the blonde goatee that has become synonymous with Branson.
Virgin Media said that it has avoided the "predictable" advertising ahead of the London 2012 Olympics, and instead featured Bolt in an executive boardroom wearing running kit and spikes, trying to persuade the viewers that he is, in fact, the Virgin founder.
However, he is interrupted by the real Branson, who makes repeated attempts to "get the usurper out of his office".
The ad, directed by Horrible Bosses helmer Seth Gordon, promotes Virgin Media's £110m network expansion plan, which also involves the firm increasing its headline broadband speed to 120Mbps.
Speaking on set, Branson said: "Virgin Media is giving customers more so what better person to champion superfast broadband than Usain Bolt? As the fastest man on the planet, he's the living embodiment of speed!"
The ad campaign, created by the DDB London agency, introduces the strapline "Keep Up", which will be used by Virgin Media in future marketing activity.
Activity has already begun on the social networks, including five-second "Bolt-on" teasers offered on Facebook, and Usain Bolt pretending to be Branson on Twitter, using the #IamRBranson hashtag.
"It is a brilliantly simple idea but the trick was to avoid the obvious sportsman endorsement cliches," said Jeff Dodds, executive director of brand and marketing communications at Virgin Media.
"We've got a long history of giving our customers more and we wanted to let them know about the exciting boost they'll soon get from us. Our competitors' customers might also feel a twinge of envy when they hear about this as what better spokesperson for our superfast broadband than Usain Bolt?
"He's the living embodiment of speed! It's a brilliantly simple idea but the trick was to avoid the obvious sportsman endorsement clichés. This is where DDB UK has done us proud by taking a refreshing, and typically Virgin self-deprecating and cheeky approach to the brief."
To promote the launch of its new 100Mbps broadband service in October 2010, Virgin Media kitted out a fleet of supercars as London taxis and gave commuters free 'super fast' rides around the capital.