Over the next few years Masiello cemented himself as a starting centre-back for Atalanta under Gian Piero Gasperini, leading them to a historic 3rd-place finish in the 2018–19 season, earning them qualification to the 2019–2020 Champions League Group Stage.
Over the next few years, Masiello became a key player for Atalanta under Gasperini, leading them to a historic third-place finish in the 2018–19 season, which secured their entry into the 2019–2020 Champions League Group Stage.