Karel Kaspar studied philosophy and Catholic theology in Pilsen and in Rome. On February 25, 1893, he received the sacrament of Holy Orders, and then worked as a pastor in Svojšín. After further studies, he was pastor from 1899 to 1920 and canon at the Prague metropolitan chapter.
Pope Benedict XV. 1920 appointed him titular bishop of Bethsaida and auxiliary bishop in Hradec Kralove. He received his episcopal consecration on April 11, 1920, the then Archbishop of Prague, František Kordač. Already in year later he became bishop of Hradec Kralove.
Pope Pius XI. conferred on him in 1931 the management of the Archdiocese of Prague and took him on 16 December 1935 as cardinal priest with the titular church of Santi Vitale, Valeria, Gervasio e Protasio in the College of Cardinals to. Karel Cardinal Kaspar took part in the conclave of 1939. He died on 21 April 1941 in Prague and was buried in St. Vitus Cathedral.