As he had been a chamberlain in Berwick, his administrative experience led him to be appointed chancellor of the Irish exchequer 20 March 1340. Before he was confirmed in his new post, the king's council in England (which had undertaken to vet all appointees to what they saw as a corrupt administration in Dublin) examined his credentials and enthusiastically endorsed his candidature. He remained as chancellor till Michelmas 1341, when he was recalled to England. On the appointment of Ralph de Ufford (qv) as justiciar, Embleton returned to Ireland again as chancellor of the Irish exchequer (26 April 1344), a post he held till June 1349. During Ufford's campaign in the west in 1344, he became treasurer of Connacht. In September 1347 he was commissioned by the king to enquire into the activities of Hugh de Burgh, chief baron of the exchequer and a former treasurer.
The anxiety in England over maladministration in Ireland, particularly in the treasury, led to a full investigation of Irish affairs, initiated at a parliament at Westminster in 1348. For many this resulted in dismissal, including the current treasurer, John Burnham (qv). Embleton was appointed deputy treasurer in his stead on 17 March 1349. The same year he also became archdeacon of Kells. He managed to stave off any threat to his position by a combination of imaginative excuses and effectively bribing the envoy sent to Ireland to examine in situ the exchequer's business. On 30 September 1349 he became treasurer of Ireland; the following month he was nominated to an important commission of oyer and terminer which concerned the activities and possible abuses of power by members of the Dublin administration below the level of chancellor and justiciar. However, within a few weeks of the arrival of the new justiciar, Thomas Rokeby (qv), he was arrested and arraigned on a host of charges ranging from robbery and extortion to rape and malicious wounding. Rokeby also claimed that he had refused to release money for a forthcoming expedition against the Irish of Wicklow.
As a consequence, on 19 January 1350 he was removed as treasurer. Embleton escaped the justiciar's wrath when Rokeby was ordered to send the disgraced former treasurer to England under safe custody to answer before the king. Edward intended to show mercy towards Embleton, whom he described as a loyal and always faithful servant. Before leaving for England, Embleton had managed to avoid facing a trial in the king's courts by claiming privilege of clergy, and before the ecclesiastical court of the archbishop of Dublin he purged his innocence.
By July 1351 Rokeby was ordered to restore all of the confiscated goods and lands. Embleton's rehabilitation was complete by 18 October 1351, when he became chief baron of the Irish exchequer. He retained this post without any serious incident till his retirement or death in September 1355.