Born at Whitehaugh, near Chinley, Derbyshire on 1 March 1715 (NS), he was one of the earliest and most significant of Wesley's lay preachers (not to be confused with the Rev. John Bennet of Laneast, Cornwall). The youngest son of dissenting parents, he attended the local Presbyterian chapel, pastored by James Clegg and was educated at Chapel-en-le-Frith and, briefly, at Findern Academy, near Derby He then became a legal clerk and then a pack-man and during that time became acquaintd with the Moravians. Following a dramatic conversion experience at Hayfield in 1742, he became associated with David Taylor and Benjamin Ingham. Joining the Methodists on 15 April 1743 he worked as a lay assistant and pioneer of Methodism in northern parts of England. He established a network of religious groups, in Lancashire, Cheshire, Yorkshire and Derbyshire, often in the face of opposition by the mob. This became known as 'John Bennet's Round' and was taken into the WM connexion. He attended John Wesley's first Conference in 1744 and was influential in establishing Quarterly Meetings and possibly the introduction of annual Conferences as features of Methodist Connexionalism.
On 3 October 1749 he controversially married Grace Murray, a widow apparently already betrothed to John Wesley, which led to an estrangement between the two men. Forming closer links with George Whitefield and his Calvinistic theology, he openly accused Wesley of preaching 'Popery' and seceded from Methodism in 1752. Supervising the Duke's Alley Chapel in Bolton, he became the founder of Congregationalism in that town. He was ordained as an Independent minister in 1754 and took charge of an Independent Chapel at Warburton, Cheshire, remaining there despite poor health until his death at Chinley on 24 May 1759.