Metropolitan Gerasimos was born on August 2, 1945 in Kalamata, Greece where he completed his primary and secondary education. In September 1969 he matriculated at Hellenic College, Brookline, MA, graduating in 1973 with a B.A. with High Distinction. He continued his studies at Holy Cross Greek Orthodox School of Theology, earning his M. Div. with High Distinction in 1976. Following graduation, he was appointed Registrar of Hellenic College/Holy Cross, a post that he held until 1979.

On December 16,1979, he was ordained to the Diaconate and appointed Archdeacon to His Eminence Archbishop Iakovos, serving in this position until 1996. From 1980 until May 1986, he was Dean of Students of HC/HC. During this period he developed the Orthodox Actionline, the telephone call-in ministry of the School. In September 1986 he entered the Master of Arts Program at Boston College. Upon successful completion of this program, he was accepted into the Doctoral Program at Boston College School of Education earning a Ph.D. in School and Counseling Psychology in June 1993. His doctoral dissertation was a study of intellectual deficits in a severe alcoholic population.

Metropolitan Gerasimos taught for a number of years at Hellenic College as well as Northeastern University, where he holds the title of Senior Lecturer. At the same time he was appointed a staff member at the Veterans Administration Medical Center (Boston), in the Department of Psychology (1991-1995). In 1990, he was reappointed as the Dean of Students at Hellenic College/Holy Cross, a post that he held until 1998, when he became Director of Admissions and Records. In 2000, he was named Administrative Assistant to the newly-elected President of Hellenic College/Holy Cross School of Theology, the Rev. Father Nicholas Triantafilou.