He was the eldest son of Mervyn Archdall (1724?–1813) of Castle Archdall, Enniskillen, Fermanagh, an MP in the Parliament of Ireland for nearly 40 years. He succeeded his father in 1813, inheriting Castle Archdale house.
Archdall joined the British Army as an ensign in the 12th Dragoons and rose through the ranks in that regiment to that of full general on 27 May 1825. He had command of the regiment under Sir Ralph Abercromby during the Egyptian campaign, losing his right arm in an impromptu cavalry charge at Lake Mareotis in 1801. As a Major-general he afterwards spent time on the staff in Ireland.
He was MP for County Fermanagh in the Parliament of the UK from 1802 to 1834 following his father, who had been a co-opted member in 1801.
He was appointed Lieutenant-Governor of the Isle of Wight for life in 1815. He was also Governor of County Fermanagh (1813–1831), Grand Master of the Orange Order (1818–1822) and a Trustee of the Irish Linen Board.
He died in 1839. He had married Jane, the daughter of Gustavus Hume Rochfort, MP and had one son and an daughter (both illegitimate). His estate passed to his brother Colonel William Archdall (1768-1857) and thereafter to his nephew Edward Mervyn Archdale, MP.
- "ARCHDALL, Mervyn (1763-1839), of Castle Archdall, Enniskillen, co. Fermanagh". History of Parliament Online. Retrieved 7 August 2016.
- The Gentleman's Magazine, Volume 12. p. 316.