Juventus have chosen previous Italy manager Spalletti to lead the team for the remainder of the campaign.
The experienced coach replaces his predecessor, who was sacked post the Lazio setback recently.
The former boss came on board in March as Thiago Motta's replacement but departed after seven months following a string of eight matches without a victory.
Under Spalletti, Napoli clinched the Serie A championship 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 where they were knocked out in the last 16 by Switzerland.
Nonetheless, Italy dismissed Spalletti in June after a World Cup qualifying defeat by Norway, putting Italy in danger of missing a third straight World Cup.
Spalletti's managerial career includes 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 during the 3-1 victory over Udinese on Wednesday which left them seventh in Serie A - six points behind leaders Napoli after nine games.
They are 25th in the league phase of the Champions League, after recording one defeat and two ties in the initial three fixtures.
