Juventus have appointed ex- Italian national team manager Spalletti as their manager for the rest of the term.
The experienced coach replaces Igor Tudor, who was let go following the loss to Lazio on Sunday.
The former boss came on board in March as Thiago Motta's replacement but left after seven months at the end of an eight-match winless run.
Spalletti guided Napoli to the Serie A crown in 2022-23 then moving on to lead the Italian national team, who had failed to qualify for the 2022 World Cup with Mancini at the helm.
He helped them qualify for Euro 2024 exiting in the last 16 stage against Switzerland.
However, Spalletti was sacked by Italy in June post a qualifying defeat against Norway, with the Azzurri at risk of missing out on a third consecutive World Cup.
Spalletti's managerial career includes Inter Milan, Roma, and Udinese in Serie A and won the Russian Premier League twice with Zenit St Petersburg.
Juventus were temporarily led by Massimo Brambilla in the midweek 3-1 triumph over Udinese moving them to seventh position in the league - six points adrift of Napoli at the top after nine rounds.
Their Champions League campaign sees them in 25th place in the group stage, having lost once and drawn twice in their opening three matches.
