Bishop Mary was born and raised in Miami, Florida. She graduated from California State University, Fullerton, in 1987 with a Bachelor of Arts in History and a minor in Music. She earned her Master of Divinity degree from the College of St. John the Evangelist in New Zealand in 1994. She was ordained in the Episcopal Church in the Diocese of Los Angeles to the diaconate in 1994, the priesthood in 1995 and to the episcopate in 2007 in the diocese of El Camino Real.
As a priest, +Mary served as assistant rector in two parishes in the Diocese of Los Angeles before accepting the call to be rector of St. Margaret’s in Miami Lakes, Florida, in December 1998. Following six years of service as rector she joined the staff of the Diocese of Southeast Florida as Archdeacon for Deployment. In November 2007 Gray-Reeves was elected as the third bishop of the Diocese of El Camino Real.