Gedson Carvalho Fernandes was born in São Tomé and moved to Portugal as a child, beginning at SC Frielas before joining Benfica's academy in 2009. He made his professional debut for Benfica B in February 2017 and was integrated into the first team for 2018/19, scoring against Fenerbahçe in a Champions League qualifier and winning the Primeira Liga title in his breakthrough season.

His progress stalled thereafter. In January 2020 he joined Tottenham Hotspur on an eighteen-month loan, which was terminated early in February 2021, and a subsequent loan to Galatasaray was also curtailed.

Beşiktaş agreed a permanent transfer in February 2022, but Turkish foreign-player quota rules meant the contract could only begin on 1 July 2022; Benfica loaned him to Çaykur Rizespor in the interim. He therefore left the club definitively at the start of the 2022/23 season without featuring under Roger Schmidt, having made around 90 competitive appearances for Benfica.