Born on May 10, 1992 in Desio, Sportiello came through Atalanta Bergamo’s youth system and then played for Seregno (2010/11 season), Poggibonsi (2011/2012 season) and Carpi (2012/13 season), before returning to Atalanta to make 88 appearances between 2013 and 2017.
In January 2017, Marco Sportiello moved to AS Fiorentina, where he played 39 games, followed by a move to Frosinone for the 2018/19 season, where he featured 36 times. Ahead of the 2019/20 season, he returned to Atalanta again and brought his appearances for his boyhood club up to 136.
Marco Sportiello has chosen the number 57 jersey at AC Milan.