Juventus have appointed previous Azzurri manager Spalletti to lead the team until the end of the season.
The experienced coach steps in for the Croatian manager, who was sacked following the loss to Lazio recently.
Tudor arrived at the club in March to replace Thiago Motta but left after seven months following a string of eight matches without a victory.
Under Spalletti, Napoli clinched the Serie A championship in 2022-23 before taking charge of Italy, after the team's failure to reach the 2022 World Cup under former boss Roberto Mancini.
He secured their spot in Euro 2024 exiting in the last 16 stage against Switzerland.
Nonetheless, Italy dismissed Spalletti in June after a World Cup qualifying defeat by Norway, as Italy faced the possibility of not making a third World Cup in a row.
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.
Massimo Brambilla took interim charge of Juventus for their 3-1 win against Udinese on Wednesday which left them seventh in Serie A - six points behind leaders Napoli after nine games.
Their Champions League campaign sees them in 25th place in the group stage, with one loss and two draws in their first three games.
