The five-time Ballon d'Or winner has repeatedly shut down suggestions of retirement in the past, but agent Jorge Mendes believes that Ronaldo will now end his career in Turin.
"I'm very happy for Cristiano. Juventus will be his last club and I'm glad he made this decision. With this team he'll close out his marvellous career," Mendes told Sport.
"I thank [Juventus president] Andrea Agnelli in particular for his determination and his willingness to negotiate with Real Madrid. And I also thank [Juventus general manager] Beppe Marotta for his professionalism."
Ronaldo scored a club-record 450 goals in just 438 games for Real Madrid, and could come up against his former club in pre-season when Juventus face the European champions on August 4.