Juventus have appointed previous Azzurri boss the veteran manager as their manager until the end of the season.
Spalletti takes over from his predecessor, who was dismissed post the Lazio setback on Sunday.
Tudor arrived at the club in March filling the shoes of Thiago Motta but left after seven months after an eight-game winless streak.
Spalletti guided Napoli to the Serie A crown in 2022-23 prior to assuming the Italy role, who had failed to qualify for the 2022 World Cup with Mancini at the helm.
He secured their spot in Euro 2024 but were eliminated in the round of 16 by Switzerland.
Yet, the Italian FA let Spalletti go in June post a qualifying defeat against 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 during the 3-1 victory over Udinese on Wednesday which left them seventh in Serie A - six points behind leaders Napoli after nine games.
They are 25th in the league phase of the Champions League, with one loss and two draws in their first three games.
