The Old Lady have chosen ex- Italy head coach Spalletti as their manager for the remainder of the campaign.
The 66-year-old replaces the Croatian manager, who was let go after the Serie A side's defeat by Lazio last weekend.
Tudor had joined the club in March to replace Thiago Motta but departed after seven months at the end of an eight-match winless run.
Spalletti guided Napoli to the Serie A crown in 2022-23 then moving on to lead the Italian national team, after the team's failure to reach the 2022 World Cup during Roberto Mancini's tenure.
He helped them qualify for Euro 2024 exiting in the last 16 stage against Switzerland.
Nonetheless, Italy dismissed Spalletti in June following a loss to Norway in World Cup qualifying, as Italy faced the possibility of not making a third World Cup in a row.
Spalletti's managerial career includes Inter Milan, Roma, and Udinese in Serie A and secured two Russian Premier League titles with Zenit St Petersburg.
Juventus were temporarily led by Massimo Brambilla during the 3-1 victory over Udinese on Wednesday moving them to seventh position in the league - 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.
