The Old Lady have chosen previous Italian national team boss the veteran manager to lead the team until the end of the season.
The experienced coach steps in for his predecessor, who was sacked post the Lazio setback last weekend.
Tudor arrived at the club in March to replace Thiago Motta but departed after seven months following a string of eight matches without a victory.
Spalletti led Napoli to the Serie A title in 2022-23 prior to assuming the Italy role, after the team's failure to reach the 2022 World Cup under former boss Roberto Mancini.
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 won the Russian Premier League twice with Zenit St Petersburg.
Massimo Brambilla took interim charge of 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.
They are 25th in the league phase of the Champions League, having lost once and drawn twice in their opening three matches.
