The Alfa Romeo name will return to Fomula One for the first time in over 30 years as a new title sponsor of Sauber, starting in 2018.
The deal came about after Sauber confirmed a new partnership with Ferrari earlier this season when a previously-agreed deal with Honda fell through. The deal with Alfa Romeo -- which is part of the Fiat Chrysler Automobiles (FCA) group -- will include "strategic, commercial and technological cooperation" between parties.
It means the team will be officially known as Alfa Romeo Sauber next year and will carry the iconic Italian company's badge. Alfa Romeo has an important part of F1's history, winning the first two world championships in 1950 and 1951 with Nino Farina and Juan Manuel Fangio. The company withdrew from F1 in 1985.
FCA CEO and Ferrari president Sergio Marchionne said: "This agreement with the Sauber F1 Team is a significant step in the reshaping of the Alfa Romeo brand, which will return to Formula One after an absence of more than 30 years.
"A storied marque that has helped make the history of this sport, Alfa Romeo will join other major automakers that participate in Formula 1. The brand itself will also benefit from the sharing of technology and strategic know-how with a partner of the Sauber F1 Team's undisputed experience.
"The Alfa Romeo engineers and technicians, who have already demonstrated their capabilities with the newly-launched models, Giulia and Stelvio, will have the opportunity to make that experience available to the Sauber F1 Team. At the same time, Alfa Romeo fans will once again have the opportunity to support an automaker that is determined to begin writing an exciting new chapter in its unique, legendary sporting history."
The news is likely to be followed by confirmation of Formula 2 champion and Ferrari junior Charles Leclerc to a race seat, on a day he was testing for the team at Abu Dhabi's Yas Marina circuit. Fellow Ferrari junior Antonio Giovinazzi has also been linked with a seat alongside Leclerc and the Alfa Romeo deal strengthens his chances.
Sauber chairman Pascal Picci is confident the news can help the team flourish.
"We are very pleased to welcome Alfa Romeo to the Sauber F1 Team. Alfa Romeo has a long history of success in Grand Prix racing, and we are very proud that this internationally renowned company has chosen to work with us for its return to the pinnacle of motorsport. Working closely with a car manufacturer is a great opportunity for the Sauber Group to further develop its technology and engineering projects.
"We are confident that together we can bring the Alfa Romeo Sauber F1 Team great success, and look forward to a long and successful partnership."