Juventus have named former Italian national team manager the veteran manager to take the helm for the rest of the term.
The 66-year-old takes over from Igor Tudor, who was dismissed following the loss to Lazio on Sunday.
The former boss came on board in March filling the shoes of Thiago Motta but exited following a seven-month stint following a string of eight matches without a victory.
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 with Mancini at the helm.
Under his guidance, they made it to Euro 2024 where they were knocked out in the last 16 by Switzerland.
Yet, the Italian FA let Spalletti go in June following a loss to Norway in World Cup qualifying, 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 lifted the Russian league trophy twice while at Zenit St Petersburg.
Massimo Brambilla served as interim manager for Juventus for their 3-1 win against Udinese on Wednesday moving them to seventh position in the league - six points adrift of Napoli at the top after nine rounds.
They are 25th in the league phase of the Champions League, after recording one defeat and two ties in the initial three fixtures.
