As in previous years, the Silver Arrows will share its reserve driver with the Woking-based outfit as part of its existing relationship that sees Mercedes power in the back of the McLaren.
Schumacher replaced Stoffel Vandoorne and Nyck de Vries as Mercedes reserve after the Belgian switched to Aston Martin and the Dutchman joined AlphaTauri as a race driver.
German Schumacher had left Haas at the end of last year after being replaced by Nico Hulkenberg.
A Tweet from the team read: "McLaren will be able to call on Mick Schumacher as a reserve driver during the 2023 F1 season as part of our arrangement with Mercedes.
"Welcome to the family, Mick."
McLaren will be able to call on @SchumacherMick as a reserve driver during the 2023 F1 season as part of our arrangement with Mercedes. Welcome to the family, Mick. 👊🧡 pic.twitter.com/DNiJ5s99rQ