The Old Lady have named previous Italian national team manager Spalletti to lead the team for the remainder of the campaign.
The 66-year-old takes over from the Croatian manager, who was sacked after the Serie A side's defeat by Lazio last weekend.
Tudor arrived at the club in March filling the shoes of Thiago Motta but departed after seven months after an eight-game winless streak.
Spalletti led Napoli to the Serie A title in 2022-23 before taking charge of Italy, who had failed to qualify for the 2022 World Cup during Roberto Mancini's tenure.
He secured their spot in Euro 2024 but were eliminated in the round of 16 by Switzerland.
Nonetheless, Italy dismissed Spalletti in June post a qualifying defeat against Norway, as Italy faced the possibility of not making a third World Cup in a row.
Spalletti has also managed 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 during the 3-1 victory over Udinese on Wednesday 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, with one loss and two draws in their first three games.
