Gerald was a nephew of the Bishop of St David's, and had a church education at Gloucester, followed by a period of study in Paris. His expectations of succeeding his uncle as bishop in 1176 were dashed, possibly because of his Welsh blood. Despite this rejection, he became chaplain to King Henry II of England in 1184, and was chosen to accompany one of the king's sons, John, on an expedition to Ireland. This was the catalyst for his literary career, his account of his findings being published as Topographia Hibernica (1188). He followed it up, shortly afterwards, with an account of Henry's conquest of Ireland.
Having thus demonstrated his usefulness, Gerald was selected to accompany the Archbishop of Canterbury, Baldwin of Exeter, on a tour of Wales in 1188, the object being a recruitment campaign for the Third Crusade. His account of that journey, the Itinerarium Cambriae (1191), remains a valuable historical document. In 1198, another opportunity arose for Gerald to become Bishop of St David's, but his application was again rejected. He repeatedly but unsuccessfully challenged this decision, made by Hubert Walter, before giving up in 1203 to spend the remainder of his life in academic study, producing works of devotional instruction and politics. He died in about 1223.