Juventus have named previous Italian national team boss Spalletti to take the helm for the remainder of the campaign.
The experienced coach replaces his predecessor, who was dismissed after the Serie A side's defeat by Lazio on Sunday.
Tudor had joined the club in March as Thiago Motta's replacement but exited following a seven-month stint after an eight-game winless streak.
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 under former boss Roberto Mancini.
He secured their spot in Euro 2024 exiting in the last 16 stage against Switzerland.
However, Spalletti was sacked by Italy 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 won the Russian Premier League twice 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 - trailing leaders Napoli by six points after nine matches.
Their Champions League campaign sees them in 25th place in the group stage, with one loss and two draws in their first three games.
