The Swede, who is now out of a drive following the collapse of Caterham, has been linked with the Swiss team in recent weeks, a time when his performances have improved consistently.
"We are pleased to announce this cooperation," said Monisha Kaltenborn. "We have got to know Marcus as a highly motivated driver. He did not have an easy rookie season this year in Formula One, however, he kept calm and improved continuously, mainly in the last races. We are convinced that signing Marcus can give the team a fresh impetus."
"Fresh from a very turbulent week, I was suddenly given my best early Christmas present ever," said Ericsson. "The Sauber F1 Team has put its trust in me for 2015, and it makes me proud, as Sauber is known to be one of the best teams in developing young drivers. It will be a great challenge. I will give my very best to develop both as a driver, and to be part of the challenge to put the Sauber F1 Team back closer to the front where it belongs."
The second driver for 2015 will be announced at a later date.
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