The 19-year-old Romanian central defender had been linked with a host of clubs, including Borussia Dortmund and Newcastle United, but has committed to Juventus until the end of the 2024-2025 season.
Dragusin, who is 1.91m tall, has been compared in his style of play to Liverpool's Virgil van Dijk and has previously highlighted the Dutchman as a player he admires.
Juventus acquired him from Romanian club Regal Sport in 2018, and this season saw Dragusin make his first-team debut in December against Dynamo Kiev in the UEFA Champions League.
His new deal was announced on the Juventus website on Saturday (AEST), with the club stating: "Dragusin's journey continues with Juve. Congratulations, Radu! See you on the pitch!"
The teenager, who has also made Serie A and Coppa Italia appearances this season, posted on Instagram: "I couldn't wait to sign the new contract with the team that have always believed in me.
"I want to thank first of all my family who have always been close to me and all the people who have helped me improve every day.
"Now is the time to demonstrate and put into play the trust that the club have given me. Come on Juve."