The 27-year-old has been linked with a move away from Chelsea for the past few seasons, coming close in 2024-25 when he joined Crystal Palace on loan before being recalled halfway through the season.
Chalobah was a key player for Chelsea last season, popping up with three goals and one assist in his 52 games across all competitions.
The arrival of Xabi Alonso meant the end of his Chelsea career, however, and with the club in need of shrinking their bloated squad, he was placed on the transfer list.
Chalobah has now completed his £30 million, including add-ons, to Fabregas’ ambitious Como side, signing a five-year deal.
Speaking to his new club’s website, Chalobah said: "I’m thrilled and honored to be here at Como: "It’s an ambitious, rising project, and working with manager Cesc Fàbregas again is truly special.
“I can’t wait to bring my experience to the team, feel the incredible atmosphere at the stadium, and connect with the fans. I will give my absolute all every single day to make history together".