The Old Lady have appointed former Italian national team manager Spalletti to lead the team for the rest of the term.
The experienced coach replaces his predecessor, who was dismissed following the loss to Lazio last weekend.
The former boss came on board in March filling the shoes of Thiago Motta 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, which missed out on the 2022 World Cup during Roberto Mancini's tenure.
Under his guidance, they made it to Euro 2024 exiting in the last 16 stage against Switzerland.
Yet, the Italian FA let Spalletti go in June following a loss to Norway in World Cup qualifying, as Italy faced the possibility of not making a third World Cup in a row.
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.
Juventus were temporarily led by Massimo Brambilla for their 3-1 win against Udinese on Wednesday moving them to seventh position in the league - six points behind leaders Napoli after nine games.
In the Champions League, they sit 25th in the league phase, with one loss and two draws in their first three games.
