It's been a bleak few seasons for the Brit, with both the driver and his team falling a long way behind their main competitors.
The 39-year-old had aimed to end his 12-year career at Mercedes on a high, and enjoyed a promising spell prior to this season's summer break, clinching victories at Silverstoneand Spa.
The move will see the Italian team up with two-time race winner George Russell from next season, as the team look to re-establish themselves as a major force in F1.
The 18-year-old has shown glimpses of his talent in the sport's second tier in 2024, winning the sprint at Silverstone before following that up with a maiden feature race triumph in Budapest.