[2] Pec made his professional debut for Vasco da Gama in a 2–0 Campeonato Brasileiro Série A loss to EC Bahia on 7 September 2019.
[3] In 2023, in the debut of the 2023 Campeonato Brasileiro Série A for Vasco da Gama against Atlético Mineiro, Pec participated in the two goals of Vasco da Gama winning 2–1 against Atlético Mineiro.
In the 23rd round, a valid game against Fluminense, Gabriel Pec came on in the 15th minute of the second half and received a yellow card.
On 30 January 2024, MLS club LA Galaxy announced the signing of Pec on a five-year Young Designated Player contract ahead of the 2024 season.
[4] Born in Brazil, Pec is of Portuguese descent and holds dual-citizenship.