James O'Brien, was born in County Longford, Ireland in 1805. O'Brien went to a local church school but one of his teachers recognised his intellectual abilities and arranged for him to be educated at the progressive Lovell Edgeworth School. In 1822 he proceeded to Trinty College, Dublin, where he won several academic prizes including the Science Gold Medal. After studying law at King's Inn, O'Brien moved to England in 1829 with the intention of becoming a lawyer in London.

In London he joined the Radical Reform Association where he met Henry 'Orator' Hunt, William Cobbett, Henry Hetherington and other leaders of the struggle for universal suffrage. In 1836 he joined the London Working Men's Association.

O'Brien began contributing articles to Henry Hetherington's Poor Man's Guardian. He signed these articles with the pseudonym 'Bronterre' and James O'Brien eventually adopted it as his middle name. He worked very closely with Hetherington and when he was imprisoned for publishing an unstamped newspaper, O'Brien took over the editorship of the Poor Man's Guardian. O'Brien and Hetherington also collaborated on other unstamped newspapers such as The Destructive and the London Dispatch. In 1837 O'Brien began publishing Bronterre's National Reformer. In an attempt to avoid paying stamp duty, the journal included essays rather than news items. During this period, Henry Hetherington and O'Brien led the struggle against the stamp duty and were consistent in their arguments that working people needed cheap newspapers that contained political information.

O'Brien was influenced by the socialist writer, Gracchus Babeuf, who had been executed during the French Revolution. In 1836 O'Brien began publishing translations of Babuef's work in the Poor Man's Guardian. He also included Philip Buonarotti's account of Babeuf and the Conspiracy of Equals. O'Brien became fascinated with the history of radicalism and began work on books on the French Revolution and the English Commonwealth. However, the authorities raided his house in 1838 and seized his manuscripts and the projects were never completed.

In 1838 O'Brien added his support for a more militant approach to winning the vote that was being advocated by Feargus O'Connor and George Julian Harney. However, O'Brien, unlike O'Connor, refused to support the use of violence to achieving universal suffrage. O'Brien argued that the Chartist should adopt a policy that was midway between the petitioning supported by William Lovett and the Moral Force Chartists, and the violence being threatened by O'Connor's Physical Force group.

After Bronterre's National Reformer ceased publication, O'Brien worked for O'Connor's Northern Star. His articles played an important role in increasing the circulation of what had become the most important of the radical newspapers. As well as writing for the Northern Star, James O'Brien also found time to publish his own newspaper The Operative.

O'Brien continued to be active in the Chartist movement and in 1840 he was arrested and charged with making a seditious speech in Manchester. He was convicted and sentenced to eighteen months in Lancaster Prison. When O'Brien was released from prison he found it difficult to continue working with Feargus O'Connor. The two men disagreed over the issue of Physical Force. Another source of dispute concerned parliamentary elections. O'Brien favoured the idea of putting up Chartist candidates whereas O'Connor preferred the tactic of putting pressure on the Whig government by threatening to vote for Tory candidates.

O'Brien finally broke with O'Connor when along with Henry Vincent and Robert Gammage he joined the Complete Suffrage Union. O'Brien continued to publish newspapers. He joined with his old friend Henry Hetherington to revive the Poor Man's Guardian in 1843 and this was followed by the National Reformer in 1844. These newspapers were not a financial success and by May, 1847, both papers had ceased publication.

After the failure of these two newspapers O'Brien concentrated on writing for other publications such as The Reynolds Weekly and the Glasgow Sentinel. He also gave public lectures and in 1851 he opened the Electric Institute in Denmark Street, Soho, London, where adult education classes were offered in English, French, science and mathematics.

By the 1850s O'Brien's poverty began to damage his health. He suffered from bronchitis and his Chartist friends attempted to raise money in recognition of the great sacrifices that he had made in the struggle to win universal suffrage and the freedom of the press. However, the damage to his health was so bad that he spent his last years bed-ridden.

James Bronterre O'Brien died on 23rd December, 1864.