The former Liverpool and Tottenham sporting director moves to Juve after a spell as president of Toulouse. Comolli resigned from TFC in May.
"I am thrilled and privileged to join a Club distinguished by its history, identity and ambitious vision,” Comolli said in a statement published on the Juventus website.
“From the very first day, I will dedicate my experience to Juventus with the ultimate goal of achieving victory — just as Juventus is meant to, and as our fans rightfully expect.”
Juve chief exec Maurizio Scanavino added: “We are delighted to welcome Damien and extend our best wishes for his journey with us. His expertise and professionalism will play a crucial role in Juventus’ path to continued strength and growth.”