The second son of the 2nd Earl of Egmont, Perceval was educated at Harrow and at Trinity College, Cambridge. He was called to the bar by Lincoln's Inn in 1786 and became a king's counsel in 1796. In that same year he entered Parliament, where his rise to power was facilitated through his contacts with William Pitt the Younger. On the formation of the government of Henry Addington (1801–04), which succeeded that of Pitt, he was appointed solicitor general. From 1802 and through Pitt's second administration (1804–06) he was attorney general.

When King George III dismissed William Grenville's ministry in March 1807, Perceval, an ardent opponent of Catholic emancipation, became chancellor of the Exchequer and chancellor of the duchy of Lancaster under the 3rd Duke of Portland, whom he succeeded as prime minister on Oct. 4, 1809. His administration was marked by strong opposition to the tolerant views that had ruined his predecessors; and he is one of the few English statesmen of the period notorious for his extreme religious intolerance. He was a man of a cold, ungenial nature. Perceval was shot and killed in the House of Commons by John Bellingham, a deranged man who had vainly applied to him for redress of a personal complaint against the government.