He started playing football at the local club academy FC Tiwinza Los Potrillos at the age of four, before moving to Sporting Cristal when he was 10.
[3] He made his debut in the Peruvian Primera División on 15 February in a 4–1 home win over newly promoted Los Chankas.
[5] He was the first 16-year-old to score for Sporting Cristal in the 21st century, and the youngest in the entire league since Luis Antonio Escobar for Alianza Lima in 1984.
[6] Three days later he played his first Copa Libertadores game in a 3–1 win at home to Always Ready of Bolivia, with his team being eliminated after losing the first leg 6–1.
[7] In September 2024, still aged 16, Castro was called up for the senior national team for 2026 FIFA World Cup qualifiers against neighbours Colombia and Ecuador.