Griffin is the twelfth of the fifteen surviving children in his family. His father, Patrick Griffin, is a brewery farmer, and his mother, Ellen Griffin, of the ancient Gaelic family of the O’Briens, is very cultivated and much interested in literature.
Griffin goes to London in 1823 and becomes a reporter for one of the daily papers. He later turns to writing fiction. One of his most famous works is The Collegians, a novel based on a trial he has reported on, that of John Scanlan, a Protestant Anglo-Irish man who murdered Ellen Hanley, a young Irish Catholic girl. The novel is adapted to the stage as The Colleen Bawn, by Dion Boucicault.
In September 1838, Griffin informs his family of his intention of joining the Congregation of Christian Brothers. He enters the novitiate at North Richmond Street, Dublin, on September 8. He embarks on his new career with intense dedication, abandoning his literary work entirely. He is then admitted to the religious habit on the feast of St. Theresa and embarks on a two-year novitiate. His distaste for his earlier vocation is allayed to the extent that he is willing to undertake the composition of a few tales of a pious nature, but he is also desperately determined to avoid as much as possible the renewal of old contacts and the reopening of painful associations. Griffin burns most all of his unpublished manuscripts, preserving only a few poems and the tragedy, Gisippus.
Gerald Griffin has a street named after him in Limerick City and another in Cork City. Loughill/Ballyhahill GAA club in west Limerick plays under the name of Gerald Griffins.