Parnell was born at East Retford, Nottinghamshire, the son of Thomas and Sarah Parnell, and was apprenticed to his father. As a teenager he became a nonconformist, visited George Fox in prison in 1653, and joined the Society of Friends.
Parnell is said to have been “young, small of stature, and poor in appearance,” but thousands in England were made to confess that “he spoke as one having authority, and not as the scribes.” He was convinced of the Truth when only fourteen years of age, and became a mighty preacher and promoter of the gospel by sixteen. Following a debate with a prominent priest, Parnell was arrested on spurious charges of being an “idle and disorderly person,” and imprisoned at Colchester Castle. There he was confined to a small hole in the thick castle wall, twelve feet above the ground. He died from sickness and ill-treatment after ten months imprisonment at the young age of nineteen. According to historian William Sewel, "So great was the malice and envy of his persecutors, that to cover their guilt and shame, they spread among the people, that by immoderate fasting, and afterwards with too greedy eating, he had shortened his days. But this was a wicked lie."
- A Trial of Faith, wherein is discovered the ground of the Faith of the Hypocrite, which perisheth, and the Faith of the Saints, which is founded upon the Everlasting Rock, London 1654. It was twice reprinted in 1655, and again in 1658. It was translated into Dutch in 1656, into French as L'Espreuve de la Foy, 1660, and into German, Amsterdam, 1681.
- The Fruits of a Fast, appointed by the Churches gathered against Christ and His Kingdom, London, Giles Calvert, 1655.
- The Trumpet of the Lord blowne, or a Blast against Pride and Oppression, London, Giles Calvert, 1655.
- A Shield of the Truth, or the Truth of God cleared from Scandalls and Reproaches, London, 1655.
- The Watcher … or a Discovery of the Ground and End of all Forms, Professions, Sects, and Opinions, London, 1655.
- Goliath's Head cut off with his own Sword; In a Combat betwixt Little David, the Young Stripling … and Great Goliath, the Proud Boaster, London, 1655. This was in answer to a paper issued against him by Thomas Drayton of Abbot's Ripon, Huntingdonshire.
He also wrote from prison, shortly before his death, epistles and addresses, as well as A Warning to all People (translated into Dutch, 1670), all of which were printed in A Collection of the several Writings given forth from the Spirit of the Lord, through … James Parnel, &c. Published in the year 1675.
- Davies, Adrian. "Parnel, James". Oxford Dictionary of National Biography (online ed.). Oxford University Press. doi:10.1093/ref:odnb/21387. (Subscription or UK public library membership required.)
- Lee, Sidney, ed. (1895). "Parnell, James". Dictionary of National Biography. 43. London: Smith, Elder & Co.
- William Sewel, The History of the Rise, Increase, and Progress of the Christian People Called Quakers, With Several Remarkable Occurrences, pg. 143"
- The Lamb's Defence against Lyes. And a true Testimony given concerning the Sufferings and Death of James Parnell. And the ground thereof. By such hands as were eye-witnesses, and have subscribed their names thereto, London, Giles Calvert, 1656.