Paulo Bernardo was formed entirely at Benfica, entering the academy as a boy and signing his first professional contract in February 2018. He progressed through the under-17, under-19 and under-23 sides before establishing himself in Benfica B, for whom he made 38 appearances and scored seven goals.

A tall, left-sided central midfielder comfortable in the advanced role, he was promoted to the first-team squad for 2020-21 and made his competitive debut that season. His most substantial spell came in 2021-22, when he was used in 24 official matches across the Primeira Liga, the Taça de Portugal and the UEFA Champions League, largely as a substitute. With the arrival of further competition in midfield he was restricted to a handful of appearances in the first half of 2022-23, his last game for the club coming in December 2022.

In January 2023 Benfica loaned him to Paços de Ferreira for the remainder of the season. He returned briefly in the summer before a further loan took him to Celtic in September 2023, where he won a Scottish league and cup double.

Celtic exercised their option in August 2024 and the transfer was made permanent, ending his association with Benfica. He was capped by Portugal at under-21 level while on the club's books.