[3] Born and raised in Martinengo, Bergamo, Casari debuted for his local club Atalanta in the 1944 regional championship and in Serie A the following year.
[2] In 1948 he was the starting goalkeeper for the national team at the London Olympics but, following a clean sheet against the United States, he conceded five goals against Denmark.
[2] He was part of the 1950 World Cup team as a reserve behind Sentimenti IV, but in the game against Paraguay Giuseppe Moro was called upon instead.
He was also known for his leadership and correct behaviour throughout his career, which earned him the nickname "il gigante buono" (the good giant).
This biographical article related to association football in Italy, about a goalkeeper, is a stub.