The pontifical garment he wore at this ceremony is now in the treasury of Saint Wenceslas Cathedral in Olmütz. After the death of Salzburg's Prince-Bishop Leopold Anton von Firmian, the cathedral chapter there chose Jakob Ernst von Liechtenstein-Kastelkorn as his successor on 13 January 1745. Due to the high debts of the archbishopric, his short reign was overshadowed by disputes with the cathedral chapter. After his death he was buried in the crypt of the Salzburg Cathedral.