Kayky da Silva Chagas was born on 11 June 2003 in Rio de Janeiro, Brazil. His path into football began with a touch of irony: initially turned away by Fluminense for lack of academy places, he joined local club Mangueira, promptly scored a hat-trick against Fluminense in his first game, and was signed by them on the spot. He rose through their youth ranks, helping the club win the 2020 Campeonato Brasileiro Sub-17, before breaking into the first team in 2021.
His early senior football quickly caught attention. In April 2021 he became the youngest player to score in the Copa Libertadores for Fluminense, netting in a 1–1 draw with Junior at just 17 years of age. That same month, Manchester City agreed a deal worth up to €10 million plus variables to sign him, with the transfer completing in August 2021. He made his City debut in January 2022, coming on as a substitute in a 4–1 FA Cup win over Swindon Town, and earned his Premier League debut the following month in a 4–0 win over Norwich City.
Loan spells at Paços de Ferreira, Bahia, and Sparta Rotterdam followed as he developed his game. He made a notable impact in his second loan at Bahia, scoring the equaliser in the Campeonato Baiano final against Vitória to seal the title. In June 2025 he joined Bahia permanently, and is currently on loan at Internacional for the 2026 season.
A left-footed right-sided forward with strong dribbling ability, Kayky has drawn frequent comparisons to Neymar for his technical skill and direct style. He has represented Brazil at youth level, featuring for the under-16 side in 2019.