William was born in Jerusalem around 1128, one of the second generation of children born to the children of the original European Crusaders in the new kingdom. As a child was educated in Jerusalem, but as an adult he may have studied in Paris, then the seat of learning in the West. There, he may have been taught by William of St. Amour.
After his return to the Holy Land in 1163 he became the leading cleric in the cathedral at Tyre, and in 1167 became archdeacon. In 1168 he went on a diplomatic mission for King Amalric to the Byzantine emperor Manuel I Comnenus, and in 1169 he was sent to Rome. On his return he became the tutor of Amalric's son and heir, Baldwin IV, who became king in 1173. In 1174 Baldwin made William his chancellor, while in 1175 William became archbishop of Tyre, gaining control over the most important matters of both Church and State.
In 1179 he attended the Third Council of the Lateran and engaged in diplomatic matters with Emperor Manuel. He returned home in 1180, but his importance ceased with the accession of Baldwin V in 1185.
William himself reports that he wrote an account of the Lateran Council which he attended, as well as a Historia or Gesta orientalium principum dealing with the history of the Holy Land from time of Muhammad until 1184. However, neither of these works have survived.
His great work is a Historia rerum in partibus transmarinis gestarum in twenty-three unfinished books. The work begins with the conquest of Syria by Omar, but most of it deals with the events that brought about the First Crusade. Although he used older, unnamed sources, the work is also valuable as a primary source itself. It was widely translated and circulated throughout Europe after William's death.
William died in Tyre in October, 1186.