Background
Castillo was born and raised in Renca, suburb of the capital Santiago.
Castillo was born and raised in Renca, suburb of the capital Santiago.
During his childhood he was part of "s supporter groups and later he joined the club"s youth ranks aged 12. In 2010 he made a goalscorer debut against San Pedro de Atacama football team for a cup game, sealing a 10–0 thrash of Católica after scoring the tenth and last goal of lieutenant The same year he was named the year’s young player of the club
As a result of his performance in the U20 World Cup, Castillo was linked with Premier League side Manchester United, where his compatriot Ángelo Henríquez was playing at the time.
Despite the rumours surrounding his movement, a transfer never materialized. In January 2014, reached an agreement to sell Castillo to Belgian Pro League side Club Brugge The move became official as Castillo signed for a fee of €3 million on a deal until 2018.
He struggled to score again the same season, but did so during the play-offs in the last game of the season against Zulte Waregem, which Brugge winning 2–0. On 28 January, he was loaned to FSV Mainz 05 until the end of the season, with an option to buy.
On 7 April, having only made one substitute appearance for the Bundesliga club, he was ruled out for the remainder of the season with damage to his right knee ligaments.
On 28 August 2015, Castillo joined Frosinone from Club Brugge until the end of the season. Castillo was listed in the 21 man squad in the Fédération internationale de football association U-20 World Cup. In the tournament, Castillo scored four goals, making him the top-scorer for Chile, including scoring an opener against Egypt.
Castillo is known for his strong dribbling skills, being a good finisher and possessing a lot of potential.
While playing in Chile, Castillo wore the number nine jersey and is compared to Swedish striker Zlatan Ibrahimović. As a result of the comparison to Ibrahimović, Castillo is often known as "Chilean Zlatan".
