[1] Occasionally appearing on stage since 2006, his breakout role was Mattia, the leading character in the Saverio Costanzo's 2010 drama film The Solitude of Prime Numbers.

[1] In 2013 he was appointed EFP Shooting Star at the Berlin International Film Festival for his performance in Paolo Virzì's Every Blessed Day.

[2] Marinelli also played a supporting role in the Academy Award-winning drama The Great Beauty by Paolo Sorrentino.

[3] He also played the antagonist Primo in the 2018 TV series Trust, and starred as Nicky in the Netflix film The Old Guard.

[4][5] In 2022, he plays Pietro Guasti in The Eight Mountains (Italian: Le otto montagne) by Felix Van Groeningen and Charlotte Vandermeersch, based on the novel of the same name by Paolo Cognetti.