Juventus have chosen previous Azzurri head coach Spalletti to take the helm until the end of the season.
The experienced coach takes over from Igor Tudor, who was let go after the Serie A side's defeat by Lazio recently.
Tudor had joined the club in March filling the shoes of Thiago Motta but departed after seven months after an eight-game winless streak.
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 under former boss Roberto Mancini.
Under his guidance, they made it to Euro 2024 where they were knocked out in the last 16 by 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 has also managed 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 in the midweek 3-1 triumph over Udinese placing them seventh in the Serie A standings - trailing leaders Napoli by six points after nine matches.
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.
