Nothing is known of Hamo's background or early years. Hamo first appears as a prebendary of the cathedral chapter of York sometime between 1162 and 1174, but he was probably a canon at York before 1171. He may have held the prebend of Husthwaite. By 1177 he had been appointed to the office of precentor of York. He held that office until at least 1195, perhaps as late as 1198, as he was mentioned in a document dated to between 1194 and 1198. In September 1189 Hamo claimed that he had been appointed to the treasurership in 1181, but did not actually hold the treasurership until 1199. In 1192 the Archbishop of York, Geoffrey tried to replace Burchard du Puiset, the Treasurer of York, with Hamo, as part of Geoffrey's disputes with Burchard and other members of the cathedral chapter. The dispute over the treasurership was resolved by the gift of a church to Hamo by Burchard and Hamo's relinquishing of any claim to the treasurership.
Hamo probably was part of a deputation to Germany by members of the cathedral chapter when Geoffrey tried to interfere in the election of a dean, against the choice of the chapter. The king, Richard, was being held prisoner there and in order to secure the royal approval for the chapter's choice, the canons had to send a deputation to the king. They were successful and secured their choice over Geoffrey's. By 1199 Hamo was treasurer of York, an office he held along with the Archdeaconry of East Riding, a combination of offices that had occurred for over 100 years. Hamo was the last treasurer to hold the East Riding alongside the treasurership. Hamo held the treasurership until at least 1216, when he last was named as treasurer. Hamo may have been Dean of York by 1217, but was certainly in office by 1 March 1218, his first appearance in documents as dean. His last certain appearance as dean was on 24 August 1219, but had been succeeded in office by Roger de Insula by early April 1220.
Besides those offices in the cathedral chapter, Hamo received the office of sacrist of chapel of St Mary and Holy Angels before 22 November 1181, when he is recorded in that office. In September 1186, Hamo was one of the candidates for the archbishopric of York put forward by the cathedral chapter, but King Henry II of England did not approve of his candidature and he did not get elected. In 1208, he had a monetary interest in Bishop Wilton.
Hamo had a son also named Hamo, who is mentioned in the records between 1199 and 1215.
' Hamo de Belers' (also spelt Beleyr, Bellers) was a Priest in the Roman Catholic Church. Not to be confused with Hamo who was Dean of York.