A Quincy native, where he was born in 1965 a son of Francis and Regina (Macdonald) Moriarty, he is the oldest of five sons; his four brothers are Kevin, Dennis, Robert, and Patrick. Raised in his native Quincy, he attended Willard Elementary School, Sterling Junior High School, and Quincy Vocational Technical School. He is an alumnus of Eastern Nazarene College, Quincy, where he graduated with a bachelor of science in business administration in 2002. He works for Arbella Insurance, Quincy. Currently serving in ministries at Holy Apostles Parish, Hanson, he also served a chaplaincy internship at South Shore Hospital, Weymouth. He is married to Michelle (Stafford) Moriarty and they are the parents of daughters Kathryn and Caroline.