De Ligt became Ajax' youngest-ever captain last year and in the past season won the Dutch league and cup double.

The 17-times capped player reached the 2017 Europa League final and scored the deciding goal as the Dutch ousted Juventus in the European Champions League quarter-finals in April.

Barcelona and Paris Saint-Germain were reportedly also interested in de Ligt but Juventus prevailed in the long battle for his signature.

De Ligt was quoted last month as saying that star striker Cristiano Ronaldo asked him to join the Bianconeri. The two spoke briefly after the Nations League final won 1-0 by Ronaldo's Portugal over de Ligt's Dutch side.

"It's the news all Bianconeri fans have been waiting to hear all summer: Matthijs de Ligt is officially a Juventus player," Juventus said.

De Ligt is the latest high-profile arrival at Juve, who have won the last eight Serie A titles but are yet to win the Champions League since their last title in 1996.

He joins a high-profile veteran backline including Leonardo Bonucci and captain Giorgio Chiellini at the club now coached by former Chelsea and Napoli helmsman Maurizio Sarri.

Veteran keeper Gianluigi Buffon has rejoined the club after one season at PSG, midfielders Aaron Ramsey and Adrien Rabiot arrived on free transfers from Arsenal and PSG respectively, and Juventus has also signed Luca Pellegrini, Cristian Romero and Merih Demirel.

De Ligt is the second star to leave the Ajax team - who apart from ousting Juventus also beat then three-time reigning European champions Real Madrid - following midfielder Frenkie de Jong's transfer to Barcelona for 75 million euros.

DPA