Feeling drawn at an early age to the Catholic priesthood, he attended St. Joseph Preparatory High School in Princeton, New Jersey.

After his ordination, the Vincentians assigned O'Connell as a teacher at Archbishop Wood Catholic High School in Warminster, Pennsylvania, where he taught religion classes and served as director of student activities.

At his inauguration, O'Connell took the controversial Oath of Fidelity, expressing his support for Ex Corde Ecclesiae, issued by Pope John Paul II in 1990.

O'Connell received his episcopal consecration on July 30, 2010, from Smith, with Archbishops John J. Myers and Donald Wuerl serving as co-consecrators, at the Cathedral of St. Mary of the Assumption in Trenton.

On February 19, 2017, O'Connell and Archbishop Christophe Pierre elevated St. Robert Bellarmine Church in Freehold, New Jersey, to the rank of co-cathedral.

[1] In August 2012, O'Connell received records showing that Fr Matthew Riedlinger had exchanged sexually explicit text messages with a person he believed to be a 16-year-old boy, then tried to set up a meeting with him.