He has now signed a two-year contract with the Italian club. Varane, a 2018 World Cup winner, previously enjoyed great success at Real Madrid, winning three La Liga titles and four Champions League trophies before spending three years at Old Trafford.
He also earned 93 caps for France before retiring from international football last year.
Como, returning to Italy's top division after a 21-year absence, appointed former Arsenal and Chelsea midfielder Cesc Fabregas as their head coach following their promotion.
"I'll be reuniting with Cesc, but this time not as a rival," Varane said. "I'm thrilled. I really admire his approach to the game and his passion for football."
