The Serie A powerhouse have appointed former Italy manager Spalletti to take the helm for the rest of the term.
Spalletti replaces Igor Tudor, who was let go post the Lazio setback recently.
The former boss came on board in March to replace Thiago Motta but left after seven months following a string of eight matches without a victory.
Spalletti led Napoli to the Serie A title in 2022-23 before taking charge of Italy, which missed out on the 2022 World Cup during Roberto Mancini's tenure.
Under his guidance, they made it to Euro 2024 but were eliminated in the round of 16 by Switzerland.
However, Spalletti was sacked by Italy in June post a qualifying defeat against Norway, putting Italy in danger of missing a third straight World Cup.
Spalletti has also managed Inter Milan, Roma and Udinese in Serie A and won the Russian Premier League twice with Zenit St Petersburg.
Massimo Brambilla served as interim manager for Juventus in the midweek 3-1 triumph over Udinese moving them to seventh position in the league - six points adrift of Napoli at the top after nine rounds.
Their Champions League campaign sees them in 25th place in the group stage, having lost once and drawn twice in their opening three matches.
