According to the press service of the club, the agreement with the 22-year-old goalkeeper is calculated until 2026.
Donnarumma's previous club was Milan, Italy, which he left this summer as a free agent.
He has 251 matches for the Rossoneri, 88 of which he played with zero.
As part of the Italian national team, he became the winner of Euro 2020 and was recognized as the best player in the tournament.
Earlier it was reported that Lionel Messi will sign a contract with Barcelona for five years.