Born in Venice, Italy, Gardelli studied with Amilcare Zanella and Adriano Ariani at the Liceo Musicale Rossini in Pesaro, and later at the Accademia Nazionale di Santa Cecilia in Rome.

In addition to vocal studies he took composition classes with Goffredo Petrassi, and later spent eight years as an assistant to Serafin, also working with Mascagni during this period.

Professionally, he continued to have a major career in Europe in addition to making recordings of many neglected operas.

[2] He was a conductor of the Danish Radio Orchestra from 1955–1961, then music director at the Hungarian State Opera from 1961 until 1966 and continued to appear in Budapest up until the 1990s.

He "showed a firm command of a work's structure and used expressive nuance with discernment, eschewing any hint of excess".