Juventus have named former Italian national team boss the veteran manager to lead the team for the rest of the term.
The 66-year-old steps in for the Croatian manager, who was dismissed after the Serie A side's defeat by Lazio last weekend.
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.
Spalletti guided Napoli to the Serie A crown in 2022-23 before taking charge of Italy, who had failed to qualify for the 2022 World Cup during Roberto Mancini's tenure.
He helped them qualify for Euro 2024 but were eliminated in the round of 16 by Switzerland.
Yet, the Italian FA let Spalletti go in June after a World Cup qualifying defeat by Norway, with the Azzurri at risk of missing out on a third consecutive 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 for their 3-1 win against Udinese on Wednesday which left them seventh in Serie A - six points adrift of Napoli at the top after nine rounds.
Their Champions League campaign sees them in 25th place in the group stage, after recording one defeat and two ties in the initial three fixtures.