In 1802 Brougham and a few friends founded the journal Edinburgh Review. In the next two years Brougham contributed thirty-five articles. At university Brougham developed radical political opinions and many of these articles dealt with the issue of social reform. The Edinburgh Review was a great success and quickly became one of the most influential political publications of the 19th century. As well as writing articles for the Edinburgh Review, Brougham wrote the book An Inquiry into the Colonial Policy of the European Powers.

Brougham worked as a lawyer in Edinburgh for three years but he came to the conclusion that his radical political views would prevent him from obtaining promotion so in 1803 he decided to move to London. In London he became friends with a group of radicals that included Thomas Barnes, William Hazlitt, Leigh Hunt, Lord Byron, and Charles Lamb.

Brougham developed a reputation as a lawyer with progressive views. This brought Brougham to the attention of the leaders of the Whigs. In 1807 Brougham was given the task of organising the Whigs press campaign in the 1807 General Election. Three years later, the Duke of Bedford, a Whig aristocrat, offered Brougham, the parliamentary seat of Camelford. The constituency only had twenty votes and they were all under the control of the Duke of Bedford. Although Henry Brougham disapproved of this corrupt system he accepted the seat in order to enter the House of Commons.

Brougham soon established himself as one of the leading radicals in Parliament. His first campaign in Parliament was against slavery and in 1810 played an important role in making participation in the slave trade a felony. The Duke of Bedford had financial problems and had to sell Camelford in 1812 and Brougham had to find another seat in the next election.

Brougham decided to become the Whig parliamentary candidate in Liverpool. This was a brave decision as Liverpool was one of the main centres of the British slave trade. Brougham was defeated by the Tory George Canning and was without a seat in the House of Commons for the next four years.

Henry Brougham continued to work as a lawyer and in August 1812 he defended thirty-eight handloom weavers who had been arrested by Joseph Nadin, Deputy Constable of Manchester, while trying to form a trade union. Their leader John Knight was charged with "administering oaths to weavers pledging them to destroy steam looms" and the rest of the men were accused of attending a seditious meeting. As a result of Brougham's brilliant defence, all thirty-eight were acquitted.

In 1815 Lord Darlington offered Henry Brougham the vacant seat of Winchelsea. Like Camelford, Winchelsea was a pocket borough. Unable to find a seat which he had a chance of winning, Brougham accepted Lord Darlington's offer and the following year became M. P. for Winchelsea.

In the House of Commons Brougham became the leading spokesmen for the radicals. In 1819 he blamed the Tory government and Manchester's local magistrates for the Peterloo Massacre. He also spoke out against the prison sentences imposed on Henry Orator Hunt, John Knight, Samuel Bamford and the other organisers of the meeting at St. Peter's Field.

Brougham was actively involved in educational reform. He supported the Ragged Schools Union, Mechanics Institutes and the Society for the Diffusion of Useful Knowledge. Brougham's ideas on state-funded education were unpopular and the education bills that he introduced to Parliament in 1820, 1835, 1837, 1838 and 1839 were all defeated.

In 1830 Brougham was given a peerage and became Lord Chancellor in Lord Grey's new Whig government. Brougham, who had been arguing for parliamentary reform for over thirty years, played an important role in persuading the House of Lords to pass the 1832 Reform Act. Lord Brougham was also one of the main people behind the passing of the 1833 Anti-Slavery Act.

Lord Brougham lost office after the defeat of the Whigs in 1834. Brougham's views were considered to be too radical by Lord Grey's successor, Lord Melbourne, and was not given government office after the Whigs returned to power in April 1835. Lord Brougham remained committed to further political reform and helped Melbourne's government pass the Municipal Reform Bill in 1835. A strong believer in equal rights for women, Brougham also played an important role in the passing of the Matrimonial Causes Act in 1857. Henry Brougham died on 17th May, 1868.