Button joins Hamilton at McLaren
Jenson Button has signed to drive alongside Lewis Hamilton in an all-English line-up at McLaren next season, BBC Sport has learned.
The world champion's move will be announced later on Wednesday.
The confirmation follows news that former world champion Kimi Raikkonen will not race in F1 next year.
The move leaves McLaren with one of the most exciting driver line-ups in F1 and Button facing arguably the toughest challenge of his career.
Button's former team Brawn, who have been taken over by Mercedes, made Button an offer, but the 29-year-old did not consider it acceptable.
Jenson Button's career in F1
His switch means McLaren will be fielding the last two world champions in the same team, Hamilton having won the drivers' title in 2008.
Button's preference for McLaren is not solely to do with money, according to sources. He also believes it is the best option for his career.
After a poor start to the 2009 season, McLaren came back strongly in the second half of the year, while Brawn, after dominating the first third of the season, slipped back in competitiveness as the year went on.
Button's manager Richard Goddard was unavailable for comment.
Brawn emerged from the ashes of the former Honda team, after the Japanese company pulled out of F1 last winter.
Button took a pay cut last winter to help secure the team's future and they went on to win the world championship together in Brawn's debut season.
Now renamed Mercedes Grand Prix, the team have already signed the German Nico Rosberg as one of their drivers.
His fellow German Nick Heidfeld is the favourite for the second seat.