The 23-year-old has joined the Rossoneri until the end of the season, Chelsea announced on Friday evening.
Milan are understood to have retained an option to buy Tomori for £25 million in the summer, following the loan.
Good luck in Italy, @FikayoTomori_! 👊🇮🇹
— Chelsea FC (@ChelseaFC) January 22, 2021
Thiago Silva‘s summer arrival at Chelsea pushed Tomori further down the Stamford Bridge pecking order, with Kurt Zouma, Toni Rudiger and Andreas Christensen all also ahead of him.
The Canada-born defender opted to stay and fight for a first-team place before the start of the campaign, but has now grasped the chance of a big loan move to Italy.
Title-chasing Milan will offer Tomori a big chance to assert his top-level credentials.
Despite his temporary departure from west London, boss Frank Lampard has insisted that Tomori still has a “long-term future” with the Blues.
“Fikayo Tomori will spend the rest of this season on loan with Serie A leaders AC Milan,” Chelsea confirmed in a statement.
“The academy graduate will continue his development at San Siro having been with Chelsea since under-eights level.
— AC Milan (@acmilan) January 22, 2021