Along with an all-new driver line-up, the famous team will also switch from Toyota power to Cosworth engines next year.
In a press statement, Frank Williams tells of his choice of experience and youth.
“Rubens needs no introduction. He is not only the most experienced driver in Formula 1, but a passionate and talented driver who fought hard for the Drivers' Championship this year,” he said.
“Nico Hulkenberg won the GP2 Championship this season as a rookie and has previously won the F3 Euroseries, Formula Masters, A1 GP and Formula BMW Germany.”
Barrichello finished third in this years Formula 1 title, taking two victories while fighting team-mate Jenson Button all the way.
German Hulkenberg dominated the GP2 Series and has impressed in all junior formula. Hulkenberg has been Williams's test driver since 2008.
Outgoing Williams drivers Nico Rosberg and Kuzuki Nakajima seem to have mixed futures. Rosberg is likely to head to Brawn, while Nakajima is unlikely to score a seat after failing to score a point during the 2009 season.