Masin was born on 31 May 1984 in Villa Ocampo, a city in the General Obligado Department of Santa Fe Province.

[3] Ahead of the 2015 legislative election, Masin was nominated as the second candidate in the Front for Victory (FPV) list to the Argentine Chamber of Deputies, behind Analía Rach Quiroga.

[6] Masin's list, which was in turn supported by former governor Jorge Capitanich, won the primary election.

[7] The Frente de Todos won 56.70% of the votes in the deputy category, and Masin was elected alongside the second candidate in the list, Aldo Leiva.

[8][9] As deputy, Masin was a vocal supporter of the legalization of abortion in Argentina, and voted in favor of the two Voluntary Interruption of Pregnancy bills that passed the Chamber, in 2018 and 2020.