De Sagastizabal had stints in the academies of Boca Juniors, Argentinos Juniors and Gimnasia y Esgrima, which preceded a move to Brown in August 2018. Signed by manager Pablo Vicó, the forward appeared as an unused substitute for a Primera B Nacional match with Guillermo Brown on 26 August. In the following September, De Sagastizabal made his professional bow in a 3–1 defeat to Atlético de Rafaela at the Estadio Nuevo Monumental; being subbed on late for Ignacio Liporace. He departed in June 2019, subsequently trialling at Italian Serie D side Este across July and August.
