In March 1794 he obtained brevet promotion to Colonel, then became a Major-General in May 1796, a Lieutenant-General in September 1803, and a full General in June 1813. In 1811, he became Colonel of the 18th Regiment of Foot.
He served in the Flanders campaigns of 1793 as aide-de-camp to Sir Ralph Abercromby, and in Ireland during the Irish Rebellion of 1798, where he was second-in-command at the Battle of Castlebar under General Lake. In 1799, he was in the expedition to the Netherlands, and was second-in-command of the 1801 expedition to Egypt, under Abercromby. Following Abercromby's death in March after being wounded at the second Battle of Abukir, Hely-Hutchinson took command of the force. In reward for his successes there, the Ottoman SultanSelim III made him a Knight, 1st Class, of the Order of the Crescent.
Hely-Hutchinson was a Member of the United Kingdom Parliament for the Irish constituency of Cork in 1801, having previously represented the city in the pre-Union Parliament of Ireland up to 1800.
The Royal Military Calendar, Or Army Service and Commission Book, ed. John Philippart. p.1, Vol II of V, 3rd edition, London, 1820. Online edition at Google Books
Parliamentary Election Results in Ireland, 1801-1922, edited by B. M. Walker (Royal Irish Academy 1978)