The Serie A powerhouse have chosen ex- Italian national team head coach Spalletti to take the helm for the rest of the term.
Spalletti replaces Igor Tudor, who was dismissed after the Serie A side's defeat by Lazio recently.
The former boss came on board in March filling the shoes of Thiago Motta but departed after seven months following a string of eight matches without a victory.
Spalletti guided Napoli to the Serie A crown in 2022-23 prior to assuming the Italy role, who had failed to qualify for 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.
Yet, the Italian FA let Spalletti go in June post a qualifying defeat against 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 won the Russian Premier League twice with Zenit St Petersburg.
Juventus were temporarily led by Massimo Brambilla during the 3-1 victory over Udinese on Wednesday moving them to seventh position in the league - trailing leaders Napoli by six points after nine matches.
In the Champions League, they sit 25th in the league phase, after recording one defeat and two ties in the initial three fixtures.
