Varane signed a free transfer to play for Italian team Como in July, but he injured his knee in his debut match against Sampdoria last month.
The center back plans to remain with the team in a non-playing capacity.
“I hold myself to the highest standard, I want to go out strong, not just holding on to the game,” he posted to his Instagram account. “It takes a big dose of courage to listen to your heart and your instinct.”
Varane started his career with Lens, a French team, however he was only in the first squad for one season before moving to Real Madrid in 2011.
During his illustrious ten-year tenure in the Spanish metropolis, he secured eighteen trophies, comprising three La Liga championships and four Champions Leagues.
After paying an initial £34 million to join to Old Trafford in the summer of 2021, the defender made 95 appearances across all competitions despite a history of injuries.
His last game for the team was an FA Cup final triumph over rivals Manchester City at Wembley in May. He won the Carabao Cup in 2022.
After making his debut for France in 2013, Varane went on to win 93 caps, the World Cup in 2018, the Nations League in 2021, and another trip to the World Cup final in 2022.