The move is worth €8m for half of the 19-year-old's economic rights, with Real Madrid retaining the other 50 per cent along with a buy-back option, standard practice in academy sales of this kind.
Valdepeñas made his first-team debut for Madrid last season away at Alaves under then-manager Xabi Alonso, and was one of three academy departures the club confirmed on the same day, alongside Gonzalo Garcia and Cesar Palacios, whose moves to Fulham brought Real Madrid's combined haul from the trio to around €58m.
Real Madrid's official statement paid tribute to a player who joined the club's youth ranks at just 11 years old: "Real Madrid CF and ACF Fiorentina have agreed the transfer of our player Victor Valdepeñas.
"Valdepeñas joined Real Madrid in 2018 at just 11 years old and has been part of our academy for six seasons. Last season he made his first-team debut and won the UEFA Youth League with the Juvenil A side. Real Madrid thanks Valdepeñas for his commitment over all these years and wishes him and his family all the best in this new stage of their lives."
Valdepeñas, who had originally come through Rayo Vallecano's academy before switching to Madrid, made 30 appearances for Castilla last season, scoring twice, and will link up in Florence with fellow Real Madrid academy product Alex Jimenez.
Speaking to Fiorentina's official channels after signing, he described the scale of the move: "I'm very happy to be here, the place is incredible, as are the facilities, and the city is beautiful. I'm really pleased to have arrived. Excited? On a scale of one to ten, I'd say twenty! I haven't had time to visit Florence yet, but the people I've spoken to have told me great things about it and I'm really looking forward to seeing it."
He also detailed his position and playing style. "The Viola Park is fantastic, from what I've been able to see so far. I was won over by talking with players who've been through the experience here — this club has a great history, and I'm aware of that even though I'm still young. I spoke with Borja Valero before coming here. My role is left-back or centre-back — if I have to choose, I'd say the first one. I think I'm an aggressive player."
He signed off with a message for the Fiorentina supporters: "I'm very excited and eager to get going. To the fans I'd say I'm happy to be here and can't wait to play my first match."
Fiorentina's statement confirmed the terms of the deal: "ACF Fiorentina announces it has acquired, on a permanent basis, the sporting rights of the player Victor Valdepenas Talavera from Real Madrid CF," with the fee set at €8m and Real Madrid holding on to both a 50 per cent sell-on clause and a buy-back option, underlining the value the Spanish club still sees in his long-term development.