Giaroli was born in Reggio Emilia in 1924, and took part in World War II as a private soldier in the Italian Navy on the Italian cruiser Bolzano.
In the aftermath of the Armistice of Cassibile, the cruiser was left afloat by Italian and Allies forces in order to prevent the Germans, who have occupied nearer La Spezia to reuse it, while the serving soldiers were left without any order. Giaroli and other Italians were captured by Wehrmacht in Marseille and taken to Germany, where they were freed by American forces at the end of the war.
At the end of the war, Giaroli returned to its native town and came through the youth ranks of Reggiana, becoming a starter for its local club for four seasons thanks to the appreciation of Hungarian managers János Vanicsek and Árpád Hajós.
He was bought by Palermo in 1949, where he spent six seasons, becoming the team captain and an iconic figure in the history of the Sicilian club. During his tenure with the "rosanero", he played with Şükrü Gülesin, Čestmír Vycpálek, Aredio Gimona, Ferruccio Santamaria and Enrique Martegani among others; the club was owned by count Raimondo Lanzia di Trabia, who refused to sell Giaroli to A.C. Milan.
During the time in Palermo, he was capped by the Italy national team B.
Giaroli transferred to Veneto side Lanerossi Vicenza, where he spent four seasons.
After his retirement in 1958, Giaroli started to coach in Reggiana youth teams.
He managed in Schio, Como, Pistoia and Carpi, and later opened some businesses in Reggio Emilia.
He died of cancer in 1991.
