Born in Viterbo, the son of a railway employee, Giustini debuted at twenty years old in The Materassi Sisters, after having been chosen through an audition.

[1] In the postwar years he was very active in the sentimental and adventurous genres, in which he usually played secondary and supporting roles.

[1][2] He was also cast in several international productions, mainly thanks to his perfect English.

[1] He retired from acting shortly after having appeared in two sci-fi films directed back-to-back by Antonio Margheriti in 1965, Wild, Wild Planet and War of the Planets.

[1][3] Giustini died in Rome on 26 October 2005, at the age of 89.