Born in Rome, Giallini is the son of a housewife and a furnace labourer.

[1] After attending the Accademia Nazionale di Arte Drammatica Silvio D'Amico,[1] he began acting on stage, working among others with Arnoldo Foà and Angelo Orlando.

[2] He appeared on several TV series and was co-protagonist, alongside Valerio Mastandrea, of the Rai Tre sitcom Buttafuori.

[2][3] In 2012 Giallini won the Nastro d'Argento for best supporting actor for his performance in ACAB - All Cops Are Bastards.

[3] He has remained a widower since July 2011, when his wife succumbed to cerebral hemorrhage.