On 4 March 2011, Pérez made his official debut for Nacional against Atlético Junior, replacing Macnelly Torres in the 86th minute. He would eventually win the 2011 Torneo Apertura with Los Verdolagas, making him the youngest player to win the honour at age 18. The following year, he was part of the Nacional squad that won both the Copa Colombia and the Superliga Colombiana, thus winning every top tier trophy in Colombia before the age of 20.
Pérez first represented the U20 Colombian national team in 2011, where he took part in the 2011 FIFA U-20 World Cup that took place in his home land. He was then recalled for the 2013 South American Youth Championship, where Colombia eventually won the championship and qualified for the 2013 FIFA U-20 World Cup. There, Pérez would give impressive performances, attracting the likes of top European teams.
Pérez was an amateur footballer, before joining Nacional in 2011, and yet was considered to be a 'pure natural talent' by the Colombian club. Often, he is a well-known versatile player mostly because of his equal footing levels with both left and right feet, as well as carrying 'panoramic vision' as shown through his countering attacking with very accurate passing. Despite committing to a defensive midfielder most of the time, Pérez has shown that he is capable of shooting on-target goals from great distances. He is often regarded very high by many top teams such as Juventus and Paris Saint-Germain because of his potential, led to being almost being signed by each respective club at one point.