In 2014, she was a member of the Venezuela national under-17 team who finished fourth in the 2014 FIFA U-17 Women’s World Cup and runners-up in the 2014 Women’s Youth Olympic football. She won the Golden Boot of the 2014 FIFA U-17 Women’s World Cup with six goals, equalling her teammate Gabriela García and was also a goalscorer of the 2014 Women’s Youth Olympic football with seven. She was also as a top scorer of the 2016 South American Under-17 Women’s Football Championship with 12. Castellanos is the top goalscorer of the Venezuela U-17 women’s team with 35. Castellanos is currently the all-time leading goalscorer of the FIFA U-17 Women’s World Cup with 11.

Castellanos was called up to the Venezuela U-20 women’s team in January 2018 for the 2018 South American Under-20 Women’s Football Championship. She was the only player to score in the Group B matches with three, once against Uruguay, Bolivia and Chile. She was also the only player to score in the final stage, scoring once in a 3–1 defeat against Paraguay U-20 women’s team.

In April 2018, Castellanos was part of the senior team in the 2018 Copa América Femenina. She scored on her debut against Ecuador on 5 April, and netted four times in an 8–0 win over Bolivia four days later.

After spending her three college years at Florida State, on 2 January 2020, Castellanos signed a two-year contract with the Spanish club, Atlético Madrid.