Fiorentina confirmed the move in a statement on Monday, ending a fraught 48 hours in Florence that began with Grosso's dismissal on Sunday night after just four competitive matches in charge.
"ACF Fiorentina announces that the management of the first team has been entrusted to Mister Paolo Vanoli. Great thanks go to the Mister for immediately and enthusiastically accepting the return to lead the first team," the club said, adding that Vanoli would take his first training session that afternoon.
Grosso, the 2006 World Cup winner who had taken over from Vanoli in the summer, won just once in the Coppa Italia before losing all three of his Serie A matches in charge, leaving Fiorentina bottom of the table having scored only once and conceded nine times. Reports on Sunday night suggested the club had also held talks with Thiago Motta before settling on a return for Vanoli instead.
Vanoli arrived at Viola Park on Monday morning alongside members of his coaching staff, where he was greeted by club representatives Giuseppe and Catherine Commisso, sporting director Fabio Paratici and general manager Alessandro Ferrari.
It is his second spell in charge of the Viola: he was appointed in November 2025 to replace Stefano Pioli with the club bottom of the table, and went on to guide them to safety, finishing 15th, though not before crashing out of the Coppa Italia early and losing to eventual Conference League winners Crystal Palace in the quarter-finals. Across 38 matches in that first stint, he recorded 14 wins, 11 draws and 13 defeats, before departing at the end of June when his contract was not renewed.
The new-old regime begins immediately with a difficult assignment away to newly promoted Venezia on Friday evening, before a first home game back at the Franchi arrives on September 15 in a Coppa Italia derby against Pisa.
Fiorentina spent more heavily than usual in the transfer market over the summer, but that investment has yet to translate into results, with the club yet to register a Serie A win this season.
Speaking in an interview just a week before his reappointment, Vanoli reflected on how his first spell had ended: "On a scale of one to ten, I'm sorry it's an eleven. Because I would have deserved it, and because I wanted to build a team in my own image. I was absolutely convinced I could take Fiorentina to a higher level.
"I was given the chance to build a dream, because with the transfer business done this year, a dream really can be built."