The move is worth around €22.5m plus a further €2m in bonuses, with Pellegrino signing a five-year contract in Florence worth approximately €1.5m per season, taking him through to 2031.
Before completing his medical, the 24-year-old posted a lengthy message on Instagram thanking the club that gave him his platform in Italian football: "Thank you, Parma. Today the moment has come to say goodbye to what, in this last period, has been my home.
"It's hard to find a place and feel part of it in such a short time. From the very first day, both my family and I felt welcomed, respected and surrounded by an affection we will always carry with us. I'm leaving with my head held high, knowing I gave everything I had, every day and every moment, for this shirt and for this city.
"I carry with me deep gratitude towards my teammates, the coaching staff, everyone I met along this wonderful journey and, above all, towards the fans. Thank you for the affection you showed me from day one and for always being there, in the good moments and the more difficult ones.
"I experienced emotions and joys that I will carry in my heart forever, just as I went through tougher moments that helped me grow. But one thing is certain: a piece of my heart will always remain in Parma. Thank you, Parma, for making me feel at home. Thank you for allowing me to wear this shirt and be part of your history.
"I have been, I am and I will always be privileged to have been part of this great family."
Pellegrino joined Parma from Vélez Sarsfield in January 2025 and made 52 appearances in gialloblù, scoring 15 goals, with his 2025-26 breakthrough season — 27 Serie A appearances, seven goals and an assist, plus three goals in two Coppa Italia matches — persuading Fiorentina to make their move.
Born in Valencia, Spain, and standing 1.92m tall, the left-footed forward began his career at Atlético Platense and Estudiantes in Argentina before his move to Vélez and then Italy.
He becomes Fiorentina's ninth signing of the summer under head coach Fabio Grosso, with the deal unlocked after Roberto Piccoli's move to Bologna cleared space and budget in the club's forward line.
Pellegrino is expected to provide competition and a different physical profile alongside Moise Kean, giving Fiorentina an aerial and hold-up option they had previously lacked in attack.