His father composed over 500 popular tunes including "Fiocca la neve".

Mario attended the Collegio San Giuseppe in Piazza di Spagna in Rome.

[3] His film debut was in 1941 in Due cuori sotto sequestro [it] (Two Hearts Seized).

[3] After a long season of successes on stage (often in couple with Riccardo Billi) Riva reached the peak of his career with the RAI variety television Il Musichiere (1957–1960), the Italian version of Name That Tune.

While he was presenting from the Verona Arena the Secondo Festival del Musichiere (a special event linked to the TV program), he inadvertently fell into a hole in the stage covered with a tarpaulin and died from his injuries a few days later.