Olivero is a product of the Lions Gibraltar youth academy, and broke into the team during the 2014-15 season at the age of 16.
In summer 2015 he had a trial at West Ham United to gain experience of professional training.
[2] He made his debut in the 2019–20 UEFA Europa League preliminary round against UE Sant Julià on 27 June.
[5] He made his debut for the Gibraltar national football team aged 17 years and 264 days on 23 March 2016, starting in a goalless draw against Liechtenstein at the Victoria Stadium - making him the territory's youngest UEFA era player at the time until Dylan Borge broke his record in March 2021.
His addition into a five-man defence by manager Jeff Wood allowed the formerly defensive Joseph Chipolina to attack.