William Wilberforce entered Parliament as member for Hull in 1780 and became a representative for Yorkshire in 1784. Initially part of a fashionable political world and a friend of William Pitt the Younger, he underwent an evangelical religious reorientation in the mid-1780s. He remained in politics, increasingly treating public service as a moral obligation. John Newton encouraged this direction, while contacts with abolitionists drew him toward a sustained campaign against the Atlantic slave trade.

From 1787 Wilberforce became the campaign's leading parliamentary spokesman. His first major Commons speech in 1789 presented evidence of the trade's brutality and argued for its abolition. Thomas Clarkson's investigations, Quaker organizing, petitions, publications, and testimony from others supplied essential support outside Parliament. Wilberforce repeatedly introduced or supported measures that failed amid commercial interests, political resistance, war, and shifting alliances. His persistence mattered, but abolition was the achievement of a broad movement that included Black campaigners and resistance by enslaved people, not the work of a single benevolent legislator.

The Slave Trade Act of 1807 prohibited British participation in the trade. It did not abolish slavery in Britain's colonies, and enforcement required further action against illegal trafficking. Wilberforce continued to press the issue and later supported a campaign against slavery itself, including the organization founded in 1823. Declining health led him to retire from Parliament in 1825, with Thomas Fowell Buxton taking a major parliamentary role. In July 1833 he learned that the abolition measure had secured decisive approval shortly before his death on July 29. The legislation received royal assent afterward and introduced a limited system of emancipation, including apprenticeship and compensation to enslavers, rather than immediate unrestricted freedom for every enslaved person.

Wilberforce's wider reform work included support for missionary and Bible societies, education, and efforts to regulate public morality. The same convictions also supported restrictive attitudes toward popular politics and working-class organization; his humanitarianism did not amount to a consistent program of democratic equality. His writings urged religious commitment among the prosperous, and his causes reflected assumptions about empire and social hierarchy.