Pierre Kalulu has signed for AC Milan from Arsenal in a deal worth €15 million, the Serie A club announced on Friday.
The Frenchman will join the Rossoneri as part of a swap deal involving Emil Krafth and Alex Iwobi, with the Gunners receiving £20m ($27m) for the Swedish defender.
Kalulu is set to make his debut against Genoa on Sunday, while he will be available for selection immediately after signing.
He joins fellow Paris Saint-Germain loanee Franck Ribery at San Siro, with both players expected to play a key role in the team's title challenge this season.
Kalulu made 88 appearances for Arsenal before being released at the end of last season, making him one of the most experienced defenders in the Premier League.
He was also part of the France squad that reached the semi-finals of the World Cup in Russia in 2018.
The signing of Kalulu by AC Milan is a significant coup for the club, who have been linked with several high-profile signings in recent weeks.
It is hoped that he can help them win their first league title since 2010, and that he can become a key player in the team's midfield.
The news comes after a disappointing season for the Rossoneri, who finished just outside the Champions League places in Serie A.
However, with the addition of Kalulu, they now have a formidable defensive unit capable of competing with any team in Europe.