The 18-year-old forward will officially join the Spanish giants next season after an agreement was reached that includes both fixed and performance-related payments.
The transfer represents the most lucrative sale of a youth player in Castellon’s history, underlining both the scale of the deal and the growing reputation of their academy.
Santamaria departs his hometown club after spending his entire development there, rising through the ranks to establish himself as one of the most exciting young attackers in Spanish youth football.
His breakthrough campaign has been defined by consistent goalscoring and rapid progression across multiple levels.
Operating primarily with the Juvenil A side, he netted 13 goals in just 17 appearances in the División de Honor Juvenil, finishing as the group’s top scorer before earning promotion.
That form earned him an early step up to Castellon B, where he continued his development against senior opposition in the Segunda Federación.
Despite the increased difficulty, Santamaria adapted quickly, adding two goals in 15 appearances while showcasing maturity beyond his years.
Across both levels, his tally of 15 goals in 32 matches highlights both his productivity and his ability to transition between youth and senior environments.
Real Madrid’s decision to invest reflects a long-term vision, with the club continuing to identify and recruit elite young talent from across Spain.
Santamaria is expected to initially integrate into the club’s development structure, where his progression will be closely managed before any potential step toward the first team.
For Castellon, the deal represents both a proud moment and a significant financial boost, while also reinforcing their ability to produce players capable of attracting the very top clubs in Europe.
Santamaria now begins the next chapter of his career with one of football’s biggest institutions, carrying both expectation and opportunity as he looks to fulfil his considerable potential.