The 22-year-old has joined the French giants in a free transfer after his contract with the Rossoneri expired.
Paris Saint-Germain have confirmed the signing of Gianluigi Donnarumma just days after the goalkeeper led Italy to Euro 2020 glory.
The Italy international left AC Milan last month after his contract with the Serie A side expired.
Donnarumma, 22, penned an open letter to bid farewell to Milan fans a day before joining the French giants on a five-year contract.
"I am very happy to be part of this great club that is Paris Saint-Germain," Donnarumma told PSG's website.
"I feel ready to take on this new challenge, and continue to grow here. With PSG, I want to win as much as possible and give joy to the supporters."
PSG president Nasser Al-Khelaïfi added: "We are pleased to welcome Gianluigi Donnarumma to Paris Saint-Germain.
"We congratulate him on his victory at Euro 2020, and his title as the best player of the competition.
"I know Gianluigi will receive a warm welcome from everyone at the club, including his team-mates, our staff and all the Parisian supporters."