Juventus have appointed previous Italian national team head coach Spalletti to take the helm for the remainder of the campaign.
The 66-year-old steps in for Igor Tudor, who was let go following the loss to Lazio last weekend.
Tudor had joined the club in March to replace Thiago Motta but left after seven months after an eight-game winless streak.
Spalletti led Napoli to the Serie A title in 2022-23 before taking charge of Italy, after the team's failure to reach the 2022 World Cup during Roberto Mancini's tenure.
Under his guidance, they made it to Euro 2024 where they were knocked out in the last 16 by Switzerland.
However, Spalletti was sacked by Italy in June after a World Cup qualifying defeat by Norway, putting Italy in danger of missing a third straight World Cup.
He has previously coached Inter Milan, Roma, and Udinese in Italy's top flight and secured two Russian Premier League titles with Zenit St Petersburg.
Juventus were temporarily led by Massimo Brambilla for their 3-1 win against Udinese on Wednesday placing them seventh in the Serie A standings - six points adrift of Napoli at the top after nine rounds.
They are 25th in the league phase of the Champions League, having lost once and drawn twice in their opening three matches.
