The change, one of the paddock's worst kept secrets, will see the Brazilian leaving Brawn after four years, having helped the team secure the constructors championship. In moving to Williams, he will go past 300 race starts, a milestone never before reached.
"Rubens needs no introduction," said Frank Williams. "He is not only the most experienced driver in Formula One but a passionate and talented driver who fought hard for the drivers' championship this year."
Barrichello will be teaming up with Williams' test driver and current GP2 champion Nico Hulkenburg, giving the Grove outfit a huge range in experience, from rookie to the most experienced driver in history.
"I am very hopeful of having a very competitive car next year, so that
is what I want from myself," explained Rubens. "I want to go on and keep on winning.
Everyone would look at a position at Williams, because it is one of the
best teams out there and it is on the way up."
Outgoing Williams driver Nico Rosberg is expected to be announced as a Brawn GP driver alongside Jenson Button in the next couple of weeks.