The Serie A powerhouse have appointed previous Italy manager Spalletti to lead the team until the end of the season.
The 66-year-old steps in for his predecessor, who was let go post the Lazio setback last weekend.
Tudor had joined the club in March filling the shoes of Thiago Motta but departed after seven months following a string of eight matches without a victory.
Under Spalletti, Napoli clinched the Serie A championship in 2022-23 then moving on to lead the Italian national team, which missed out on the 2022 World Cup with Mancini at the helm.
Under his guidance, they made it to Euro 2024 exiting in the last 16 stage against Switzerland.
Nonetheless, Italy dismissed Spalletti in June post a qualifying defeat against Norway, putting Italy in danger of missing a third straight World Cup.
He has previously coached Inter Milan, Roma, and Udinese in Italy's top flight and lifted the Russian league trophy twice while at Zenit St Petersburg.
Massimo Brambilla served as interim manager for Juventus during the 3-1 victory over Udinese on Wednesday placing them seventh in the Serie A standings - six points behind leaders Napoli after nine games.
Their Champions League campaign sees them in 25th place in the group stage, having lost once and drawn twice in their opening three matches.
