The Italian team announced the deal on Thursday afternoon, less than 24 hours after initial reports of the move started to break.
Hamilton and Ferrari took advantage of a break clause in the Brit's contract with Mercedes - a contract signed just months ago - which allows him to opt out of the new deal after a single season.
There appears likely to be a break clause in his new Ferrari deal too, which the team described in a statement as 'multi-year'.
Lewis Hamilton will replace Carlos Sainz at Ferrari in 2025
Turrini: Hamilton signed a 2+1 contract
Ferrari's statement was light on details, just 20 words long, but Italian Formula 1 journalist Leo Turrini revealed further information on Sky Sport 24.
“It's the news of the millennium for F1," he said. "Hamilton signed a 2+1 contract, also with a view to 2026. Lewis dressed in red was a hypothesis that seemed to belong to the wildest dreams.
"We are in the presence of a historic event, such a successful driver has never arrived at Ferrari. Michael Schumacher had won two championships when he arrived. We are in the presence of something extraordinary. As Mogol writes: whether it will work or not, we will only find out by living."
That information from Turrini suggests that Hamilton will be in red until at least the end of the 2026 season, and at least a season longer if they impress him with their first car after the 2026 regulation changes.
GP BAHRAIN
29 Feb - 2 Mar
GP SAUDI ARABIA
7 - 9 Mar
GP AUSTRALIA
22 - 24 Mar
GP JAPAN
5 - 7 Apr
GP CHINA
19 - 21 Apr
GP USA
3 - 5 May
GP ITALY
17 - 19 May
GP MONACO
24 - 26 May
GP CANADA
7 - 9 Jun
GP SPAIN
21 - 23 Jun
GP AUSTRIA
28 - 30 Jun
GP GREAT BRITAIN
5 - 7 Jul
Gulf Air Grand Prix of Bahrain 2024
Grand Prix of Hungary 2024 
Grand Prix of Belgium 2024 
Grand Prix of Azerbaijan 2024 
Grand Prix of Singapore 2024 
Gran Premio de la Ciudad de Mexico 2024 
Grande Prêmio de São Paulo 2024 
Qatar Grand Prix 2024 
Grand Prix of Abu Dhabi 2024 
Innovatieweg 20C