The Serie A powerhouse have named former Italian national team head coach the veteran manager to take the helm for the rest of the term.
The experienced coach replaces his predecessor, who was let go post the Lazio setback recently.
Tudor had joined the club in March filling the shoes of Thiago Motta but left after seven months at the end of an eight-match winless run.
Under Spalletti, Napoli clinched the Serie A championship 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.
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 during the 3-1 victory over Udinese on Wednesday placing them seventh in the Serie A standings - trailing leaders Napoli by six points after nine matches.
In the Champions League, they sit 25th in the league phase, with one loss and two draws in their first three games.
