Juventus have chosen previous Azzurri head coach the veteran manager as their manager for the rest of the term.
The 66-year-old takes over from the Croatian manager, who was dismissed post the Lazio setback last weekend.
Tudor had joined the club in March filling the shoes of Thiago Motta but departed after seven months following a string of eight matches without a victory.
Spalletti guided Napoli to the Serie A crown in 2022-23 then moving on to lead the Italian national team, who had failed to qualify for the 2022 World Cup during Roberto Mancini's tenure.
Under his guidance, they made it to Euro 2024 exiting in the last 16 stage against 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.
He has previously coached Inter Milan, Roma, and Udinese in Italy's top flight and won the Russian Premier League twice with Zenit St Petersburg.
Juventus were temporarily led by Massimo Brambilla for their 3-1 win against Udinese on Wednesday which left them seventh in Serie A - trailing leaders Napoli by six points after nine matches.
They are 25th in the league phase of the Champions League, having lost once and drawn twice in their opening three matches.
