Sebastian Vettel will drive for a Racing Point team rebranded as Aston Martin next season after completing a multi-year deal with the team.
The four-time world champion, deemed surplus to requirements by Ferrari, will head up the project.
Vettel's announcement hijacks Ferrari’s 1,000th Grand Prix at the Italian team’s home track in Mugello this weekend.
The 33-year-old German will team up with Lance Stroll, 21, the son of Canadian fashion billionaire Lawrence Stroll, a co-owner of Racing Point.
The announcement comes after Sergio Perez revealed on Wednesday night that he was no longer wanted by Racing Point after seven years with the Silverstone-based team.
Vettel said: "I’m extremely proud to say that I will become an Aston Martin driver in 2021. It’s a new adventure for me with a truly legendary car company.
"I have been impressed with the results the team has achieved this year and I believe the future looks even brighter.
"I still have so much love for Formula 1 and my only motivation is to race at the front of the grid. To do so with Aston Martin will be a huge privilege."
Team principal Otmar Szafnauer added: "Sebastian is a proven champion. On a Saturday or Sunday afternoon, Sebastian is one of the best in the world, and I can’t think of a better driver to help take us into this new era."
Vettel heads into the ninth round of 17 this weekend a lowly 13th in the championship following the worst campaign of his career.
He will be replaced by current McLaren driver Carlos Sainz at Ferrari next year, following Charles Leclerc’s emergence as the Italian team’s pick to end a drivers’ championship drought which stretches back to 2007.
Vettel, who won four consecutive titles with Red Bull between 2010 and 2013, and in terms of victories is the third most successful in the sport’s history behind only Michael Schumacher and Lewis Hamilton, was signed by Ferrari to end that period without success.
But the Italian hierarchy grew tired of a number of error-strewn seasons by Vettel which allowed Hamilton to march to the last three world championships.
Leclerc’s arrival last year hastened his exit, with Ferrari not even entertaining offering Vettel an extension to his deal which expires at the end of the year. Vettel will hope the move to Racing Point will breathe fresh life into his career.
Racing Point have been in the spotlight this year after they were docked 15 points and fined for copying parts of the Mercedes that Hamilton drove to last year’s title. They are fourth in the constructors’ standings, two places ahead of Ferrari.