Harlech was the eldest son of William Ormsby-Gore and Mary Jane Ormsby. He was elected to the House of Commons for Carnarvonshire in 1837, a seat he held until 1841, and later represented North Shropshire from 1859 to 1876. The latter year he was raised to the peerage as Baron Harlech, of Harlech in the County of Merioneth, with remainder to his brother William.
Lord Harlech married Sarah, daughter of Sir John Tyssen Tyrrell, 2nd Baronet, in 1844. He died in June 1876, aged 60, having held the title for only five months. He was succeeded according to the special remainder by his brother William. Lady Harlech died in 1898.