Evangelist and hymnwriter, he was born in Reading, the son of George and Anna Cennick, on 12th December, 1718. He was raised in a strict Anglican home, although his paternal grandparents had been Quakers who suffered imprisonment for their beliefs. After a few years of teenage rebellion and worldly pursuits, he became deeply concerned about his neglect of spiritual commitment and passed through a period of heart-searching and repentance until words from Psalm 34:19-20 ('Many are the afflictions of the righteous, but the Lord delivereth him out of them all. The Lord redeemeth the soul of his servants; and none of them that trust in Him shall be desolate') which he heard in a church service, brought him peace and an assurance of God's love on 7 September 1737. He became extremely zealous of spiritual life, and hearing locally of Charles Kinchin (a member of Wesley's Holy Club), he travelled to Oxford to seek him out and this led to his making the acquaintance of both Whitefield and John Wesley.
He first met Wesley in Reading on 9 March 1739 and, as a result was invited to assist in the school for colliers' children which Wesley and Whitefield were jointly setting up at Kingswood near Bristol. Arriving there in June, 1739, he found himself unexpectedly drawn into open-air preaching in which Wesley seems actually to have encouraged him; so he may well have been the first Wesleyan lay preacher. The two fell out, however, over Christian Perfection, to which Cennick strongly objected while at the same time openly criticizing the Wesleys' Arminianism, which led to his suspension from membership in the Kingswood Society in 1741.
Joining Whitefield in London, Cennick became his associate and had pastoral charge of the Moorfields 'Tabernacle' in Whitefield's absence. He also conducted a campaign of evangelisation in north Wiltshire, raising up a network of societies. After a while, however, he found disputes among the Calvinists about antinomianism] just as hard to bear as Wesleyan claims to perfection and switched his allegiance to the [[Entry:1984 Moravians, who seemed to avoid both extremes. He formally joined them in December 1745 taking his societies with him. After a three-months visit to the church's headquarters at Herrnhut in Saxony, he crossed to Ireland in 1746 and, except for short periods, spent the rest of his short life over there. First preaching in a Baptist hall in Skinners Alley, Dublin, where he drew huge crowds, he then travelled throughout the northern counties, where he is credited with having started some two hundred societies. Only four of these remain. His reference in a sermon to 'the Babe that lay in swaddling clouts' is said to have led to the Irish Methodists being dubbed 'Swaddlers'. He was ordained a Moravian deacon in 1749.
A volume of his sermons is said to have been the means of James Montgomery's conversion. Cennick himself published three volumes of hymns, few of which are in use now. Three of them were in the 1933 Methodist Hymn Book: 'Thou great Redeemer, dying Lamb' (104), 'Children of the heavenly King' (696) and the evening hymn, 'Ere I sleep' (947), only the last of which survived into Hymns and Psalms. But his well-known grace, 'Be present at our table Lord', helps to keep his memory alive. His autobiography (2nd edition, 1745) includes 'an account of the trials and temptations which he endured'.
He died in London on July 4th, 1755, and was interred in the Moravian cemetery at Chelsea.