Pope Pius IX served as head of the Catholic Church from 1846 to 1878, marking the longest verified papal reign at 31 years, 7 months, and 23 days.
The Catholic Church has witnessed several papacies of remarkable duration. Saint Peter, traditionally recognized as the first Pope, is believed to have served for 34 years, though the exact dates remain unverified.
Pope Pius IX holds the record for the longest confirmed papal reign, serving from 1846 to 1878, a tenure lasting 31 years, 7 months, and 23 days. Following him, Pope John Paul II reigned from 1978 to 2005, totaling 26 years, 5 months, and 18 days. Other notable long-serving pontiffs include Pope Leo XIII (25 years, 5 months), Pope Pius VI (24 years, 6 months), and Pope Pius VII (23 years, 5 months).