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.
In the following years, Masiello solidified his position as a starting center-back for Atalanta under Gian Piero Gasperini, leading them to a historic third-place finish in the 2018–19 season, which earned them a spot in the 2019–2020 Champions League Group Stage.