Pending a medical, Fiorentina will pay €8m for 50 per cent of the 19-year-old defender's rights, with Real Madrid retaining the other half along with a buy-back option for future years. The Castilla regular will sign a five-year contract in Florence.
Valdepenas made his first-team debut for Real Madrid last season under Xabi Alonso, starting away at Alaves in Mendizorroza. A fixture in the Castilla side under both Alvaro Arbeloa and Julian Lopez de Lerma, his versatility across central defence and left-back has been one of his biggest assets.
His market value stood at €5m while still a Castilla player, underlining the scale of his potential and explaining Fiorentina's determination to land one of the standout names from the club's Youth League-winning squad in April.
The move takes Real Madrid's income from player sales this summer to €134.5m, with Mario Martin, Nico Paz, Alex Jimenez, Alvaro Rodriguez, Fran Garcia, Mario Gila and Victor Munoz also among the Real-connected sales that have brought money into the club's coffers.
Fiorentina, meanwhile, have been busy on multiple fronts as they reshape their squad. The club have also reached an agreement with Wrexham for the sale of Matias Moreno, who spent last season on loan at Levante. Should the move go through as planned, the Championship club would pay around €8.5m for the 22-year-old defender, with Fiorentina retaining 50 per cent of any future sell-on fee.
A separate departure could see Nicolas Valentini return to South America, with Fiorentina having reached an agreement with Gremio for the Argentine defender. The Brazilian club, fresh from selling Viery, are prepared to pay around €3.5m for the 2001-born centre-back, with the move now dependent on the approval of both players before it can be finalised.
On the incoming side, Fiorentina are also negotiating a move for Trabzonspor midfielder Christ Ravynel Inao Oulai, while sporting director Fabio Paratici is looking to accelerate a separate deal for RB Leipzig winger Johan Bakayoko.
The Belgian, valued by the German club at around €20m, has been on Fiorentina's radar throughout the summer, with Paratici hoping to advance the move in the coming days to strengthen Fabio Grosso's attacking options in his 4-3-3 system.