Born Selina Shirley, on 13 August 1707 (OS), daughter of the first Earl Ferrers. She married Theophilus, Earl of Huntingdon in 1728 and lived at his Leicestershire seat, Donington Park and in London. They came under Moravian influence through Benjamin Ingham, were converted in 1739 and from 1741 were associated with the Wesleys. The Earl's religious convictions were less deeply rooted than those of his wife, who was drawn to the Wesleys' teaching on Christian perfection.
After his early death in 1746, she successfully managed the extensive family estates, including Donington Park, and dedicated much of her life to supporting the evangelical cause, initially from her Leicestershire base and among her aristocratic acquaintances. Becoming increasingly associated with George Whitefield, Howell Harris and the Calvinistic Methodists, she opened chapels in many places, including such fashionable resorts as Bath and Brighton (1765) and Tunbridge Wells (1769). Evangelical clergy, William Romaine and Martin Madan, were appointed as her 'chaplains'. Failing to get the support she needed from the Anglican hierarchy, she sponsored a number of Evangelicals seeking ordination, appointing some of them as chaplains.
In 1768, following the expulsion of six evangelical students from St. Edmund Hall, Oxford, she founded a college at Trevecka to train young men for the ministry. Whitefield bequeathed her the 'Orphan House' at Bethesda, Georgia, which she ran after his death, but lost after the Revolutionary War. Her proprietorial attitude to the college at Trevecka annoyed John Wesley and she was increasingly influenced by the ultra-Calvinism of Augustus Toplady. Though she did not actively participate in the Calvinistic controversy of the 1770s, she used her influence to oppose the Arminians. Legal action over her Spa Fields chapel and her controversial appointment of an increasing number of 'chaplains' led to the formation of the Connexion which bears her name. She died on 17 June 1791.
See also Countess of Huntingdon's Connexion.