Raised at Ourique DC in the Alentejo, João Rego joined Benfica's academy in 2018 and progressed quickly through the Seixal ranks, signing his first professional contract in February 2021 at just sixteen years of age.

The attacking midfielder made his senior bow for Benfica B in September 2023, coming off the bench in a Liga Portugal 2 draw with Leixões, and later committed his future to the club until 2028. Comfortable operating between the lines and blessed with a refined technical touch, he combined regular football with the reserves with a growing role alongside the first team, where he wears the number 84 shirt. He was part of the squad that lifted the Taça da Liga in 2024/25.

Rego has been a constant at international level, representing Portugal at Under-17, Under-18, Under-19 and Under-20 level and finding the net at each of those age groups.