The Serie A powerhouse have named former Azzurri boss the veteran manager to lead the team until the end of the season.
The experienced coach replaces his predecessor, who was let go post the Lazio setback last weekend.
Tudor arrived at the club in March filling the shoes of Thiago Motta but departed after seven months at the end of an eight-match winless run.
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 during Roberto Mancini's tenure.
He secured their spot in 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, with the Azzurri at risk of missing out on a third consecutive World Cup.
Spalletti has also managed Inter Milan, Roma and Udinese in Serie A and secured two Russian Premier League titles with Zenit St Petersburg.
Massimo Brambilla took interim charge of Juventus in the midweek 3-1 triumph over Udinese 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, after recording one defeat and two ties in the initial three fixtures.
