The move, which is expected to be formally announced today, sees Hamilton sever a longstanding tie with McLaren, who he has been with in various guises since he was 13 years old. His replacement will be Sauber driver Sergio Perez.
His move, though, has wider repercussions other than just for McLaren, as current Mercedes driver Michael Schumacher has had to make way for the new, younger arrival.
Hamilton will join current Mercedes driver Nico Rosberg with the German seven-time world formula one champion facing a tough decision – to seek a new team for next season or to return to retirement.
Hamilton is to be given number one spot at the team – and will receive an increased salary, too – but it is the premier position he will be afforded and the chance to push for more world titles to add to the solitary one he was won so far, that will most likely have been the deal clincher for the 27-year-old Brit.