The Old Lady have named ex- Azzurri manager Spalletti as their manager until the end of the season.
Spalletti steps in for the Croatian manager, who was let go post the Lazio setback on Sunday.
Tudor had joined the club in March filling the shoes of Thiago Motta but exited following a seven-month stint following a string of eight matches without a victory.
Under Spalletti, Napoli clinched the Serie A championship in 2022-23 prior to assuming the Italy role, after the team's failure to reach the 2022 World Cup during Roberto Mancini's tenure.
He helped them qualify for Euro 2024 where they were knocked out in the last 16 by Switzerland.
Nonetheless, Italy dismissed Spalletti in June post a qualifying defeat against Norway, with the Azzurri at risk of missing out on a third consecutive 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 moving them to seventh position in the league - six points adrift of Napoli at the top after nine rounds.
In the Champions League, they sit 25th in the league phase, with one loss and two draws in their first three games.
