The Italian champions have made the decision to obtain full ownership from lower-league Pro Vercelli, after the promising youngster impressed during pre-season
The centre-back joined the Serie A champions on a co-ownership deal earlier this summer, and has since impressed enough to prompt the Old Lady to obtain full ownership.
"Promising defender Alberto Masi has joined Juventus on a permanent deal after the remainder of his registration rights were purchased from Pro Vercelli," a statement on the Juve website reads.
"The 19-year-old initially agreed terms on a co-ownership agreement signed on 6 July. But following a string of impressive pre-season displays, the Bianconeri have elected to buy out the other half of his contract."
Masi recently made his debut for Italy Under-21 in the friendly against Netherlands, and is seen as one of Italy's best defensive talents.