The Serie A powerhouse have named previous Italy manager Spalletti to take the helm for the rest of the term.
Spalletti replaces the Croatian manager, who was dismissed after the Serie A side's defeat by Lazio recently.
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.
Spalletti guided Napoli to the Serie A crown in 2022-23 before taking charge of Italy, which missed out on the 2022 World Cup with Mancini at the helm.
He helped them qualify for Euro 2024 but were eliminated in the round of 16 by Switzerland.
However, Spalletti was sacked by Italy in June after a World Cup qualifying defeat by 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 won the Russian Premier League twice with 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 adrift of Napoli at the top after nine rounds.
In the Champions League, they sit 25th in the league phase, having lost once and drawn twice in their opening three matches.