|Date of birth||17 May 1997|
|Place of birth||Sint-Truiden, Belgium|
|Height||1.74 m (5 ft 8 1⁄2 in)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 9 May 2018|
He started his football career at Gelmen V.V. under the coaching of his father, where also his three year older brother played. He was soon noticed by a scout from Standard Liège and shortly after moved to the club where he played for seven years. He later moved to R.S.C. Anderlecht.
Castro-Montes was born in Belgium to a Spanish father and a Belgian mother.
- Alessio Castro-Montes at Soccerway
- EXCL. PORTRET: CASTRO MONTES NU WEL KLAAR VOOR BELGISCHE TOPCLUB, voetbalbelgie.be, 7 June 2019
- Alessio Castro-Montes wechselt von der KAS Eupen zu KAA Gent, as-eupen.be, 17 June 2019
- DH.be. "Alessio Castro Montes : "Je voulais un sacre chez les jeunes"".