[1] He was ordained as a priest on 20 September 1834 and was placed in the service of the Diocese of Nola where he remained until 1851 under Bishop Gennaro Pasca.

In 1851 he was ordained Bishop of Castellaneta and served the diocese for 9 years until, in 1860, anticlericalists tried to assassinate him by firing four bullets into his carriage.

The fourth bullet, which would likely have been fatal, hit D'Avanzo's pectoral cross and he survived the attempt.

In 1876 he was elevated to Cardinal by Pope Pius IX and was appointed Cardinal-Priest of Santa Susanna.

[3] Throughout his career he was a strong advocate against Freemasonry and led a number of Church campaigns against the society.