Fr. Shaunessy served Catholics on the city's north side and in north Cook County for over 30 years beginning in 1945 with his appointment as assistant pastor of St. Francis in Wilmette. For 11 years, beginning in 1953, he was the assistant pastor of St. Mel Parish in Chicago. Following that appointment, he served as assistant pastor for four years each at Queen of Angels and St. Raphael, both in Chicago.

In 1972, Fr. Shaunessy was appointed administrator and then pastor of St. Eugene Parish in northern Cook County. He served there for 19 years before his retirement from active ministry in 1991. He was made pastor emeritus of St. Eugene in that year.

An Oak Park native, Fr. Shaunessy attended schools in Forest Park before enrolling in Quigley Preparatory Seminary. He graduated from the University of St. Mary of the Lake Seminary in Mundelein in 1945, the same year he was ordained for the Archdiocese.

For a decade beginning in the 1950s, Fr. Shaunessy served three Chicago Catholic high schools in various capacities. He was a chaplain and teacher at Siena High School in the mid 1950s and was a counselor at St. Mel High School from 1953 to1964 and at Providence High School from 1957-1962 before they were merged as one school.

Visitation for Fr. Shaunessy will take place on Monday. June 7, at St. Eugene Church, 7958 W. Foster Ave., Chicago, from 3 to 9 p.m. Fr. Patrick Lyons, pastor of Our Lady of Knock Parish in Calumet City, will preside at a funeral liturgy for Fr. Shaunesy on Tuesday, June 8, at 10:30 a.m. at St. Eugene. Interment is at Queen of Heaven Cemetery, Hillside.