The Serie A club will pay an initial loan fee of around 2.1 million pounds for the Senegal international, with a further 23.6 million pounds due if the conditions attached to the obligation to buy are triggered.
The move gives the 23-year-old an opportunity to secure a more prominent role at one of Europe's biggest clubs.
Sarr had fallen down the midfield pecking order at Spurs following the arrivals of Sandro Tonali and Mateus Fernandes, while head coach Roberto De Zerbi confirmed that the midfielder had asked to leave in search of more regular first-team football.
Juventus moved quickly to secure his signature despite reported interest from clubs in France, Turkey and the Premier League.
Sarr joined Tottenham from Metz in August 2021 and initially returned to the French club on loan. He went on to make 141 appearances for Spurs in all competitions, scoring 11 goals and providing 11 assists.
He made 105 Premier League appearances and played a significant role in Tottenham's 2024/25 Europa League triumph.
His cross for Brennan Johnson's winning goal against Manchester United in the final in Bilbao was one of the defining moments of that campaign, helping Tottenham claim their first major trophy in 17 years.
Sarr also leaves Spurs as an established Senegal international, having won 42 caps since making his debut in 2021. He was part of the Senegal squad that won the Africa Cup of Nations in 2022.
The midfielder said goodbye to Tottenham's supporters in a message posted on social media.
"Thank you, Tottenham, for all the wonderful years we've spent together. A special thank you to the fans for their incredible support and love. See you again very soon," Sarr wrote.
At Juventus, Sarr will add energy, athleticism and versatility to the midfield as the Turin club targets a return to the Champions League places.
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