Guilherme was born in São Paulo, and joined Grêmio's youth setup in May 2014, from Cotia [pt], after a trial period.

[2] Back to the Tricolor in May 2016, Guilherme made his first team – and Série A – debut on 29 June, coming on as a late substitute for Everton in a 3–2 home win over Santos.

[9] An immediate starter, he scored his first goals for the club on 7 March, netting a brace in a 3–2 home win over Al Nassr.

On 9 February 2023, after losing space at Grêmio, Guilherme was loaned to Fortaleza in the top tier, until December.

[13] He was the club's top goalscorer in their 2023 Copa Sudamericana run, as they lost the final to LDU Quito.