Maualuga was born at Reynolds Army Community Hospital in Fort Sill, Oklahoma, to American Samoan parents, Talatonu and Tina Maualuga. His father, Talatonu, was in Oklahoma serving with the United States Army. Within a few months, the family moved to Waipahu, Hawaii, on the island of Oahu. Financially, the family struggled in Hawaii. While in sixth grade, Maualuga started playing football because he saw the popular kids played football and carried their pads and helmets to school. Not only was Maualuga passionate about football, he also had a love for attending church with his family. His family attended First Samoan Full Gospel Pentecostal Church in Waipahu and Moanalua, where Rey was a member of the FSFGPC youth group. After sixth grade, his family moved to Oxnard, California as his father pursued Pentecostal ministry. He spent his first year of high school in nearby Ventura before moving up to Eureka in Northern California where his father practiced ministry.