As a youth Raleigh served (1569) as a volunteer in the Huguenot army in France. In 1572 he was listed as an undergraduate at Oxford, where he may have studied before going to France, and his name appears in the registry of the Middle Temple in 1575. In 1578, Raleigh and his brother Carew joined their half brother Sir Humphrey Gilbert in outfitting a heavily armed fleet, ostensibly for a “voyage of discovery.” Storms and desertions soon ended the project. In 1580, Raleigh served in Ireland, suppressing the rebels in Munster.

When he returned to England in 1581, Raleigh immediately went to court and soon became a favorite of Queen Elizabeth I. Whether he placed his cloak in the mud for Queen Elizabeth I or not, it seems fairly certain that his personal charm had much to do with his friendship with her. As an important courtier he was granted (1583) a wine monopoly, was knighted (1585), and was given vast estates in Ireland. Made warden of the stanneries (the tin mines of Cornwall and Devon) in 1585, Raleigh exhibited a genuine talent for administration, but he had already alienated too many important people to achieve real political power. He was appointed captain of the queen's guard in 1587, an office significant because it required constant attendance on Elizabeth.

Raleigh conceived and organized the colonizing expeditions to America that ended tragically with the “lost colony” expeditions on Roanoke Island, N.C. He was later named a member of the commission for the defense against Spain, but it is doubtful that he participated in the naval operations against the Spanish Armada (1588). Probably because of his conflict with Robert Devereux, second earl of Essex, Elizabeth's new favorite, Raleigh left court in 1589. At Kilcolman Castle, Ireland, he became a close friend of Edmund Spenser, whose Faerie Queene, begun under the aegis of Sir Philip Sidney, was continued under Raleigh's patronage.

After the queen's quarrel with Essex over the earl's marriage, Raleigh returned to prominence at court and was granted (1592) an estate at Sherborne. Later that year he set out on a privateering expedition, but he was recalled by Elizabeth and imprisoned in the Tower of London when she learned of his secret marriage to Elizabeth Throckmorton, a maid of honor at court. Late in 1592, Raleigh's expedition returned to England with a richly loaded Portuguese carrack. Disputes broke out over the division of the spoils, and Raleigh was released to quell the disturbance, thereby winning his freedom.

Barred from the court, Raleigh sat in Parliament. He achieved great notoriety for his connection with the poetic group known as the “school of night.” Led by Thomas Harriot and including Christopher Marlowe and George Chapman, the group's skeptical attitude and critical interpretation of Scripture won them a reputation for atheism.

In 1595, Raleigh embarked on an expedition with the adventurer-scholar Laurence Kemys to find the fabled city of El Dorado. They penetrated 300 mi (480 km) up the Orinoco River into the interior of Guiana, bringing home specimens containing gold. Raleigh published his Discovery of Guiana the following year. In 1596 he commanded a squadron in the English expedition against Cádiz.

Raleigh was made governor of Jersey in 1600, but his fortunes ebbed when he drifted apart from his former ally Robert Cecil (later earl of Salisbury) in the political tempest over Essex's treason and death. He met his downfall upon the accession (1603) of James I, who had been convinced by Raleigh's enemies that Raleigh was opposed to his succession. Many of Raleigh's offices and monopolies were taken away, and, on somewhat insufficient evidence, he was found guilty of intrigues with Spain against England and of participation in a plot to kill the king and enthrone Arabella Stuart. Saved from the block by a reprieve, Raleigh settled down in the Tower and devoted himself to literature and science. There he began his incomplete History of the World.

Raleigh was released in 1616 to make another voyage to the Orinoco in search of gold, but he was warned not to molest Spanish possessions or ships on pain of his life. The expedition failed, but Laurence Kemys captured a Spanish town. Raleigh returned to England, where the Spanish ambassador demanded his punishment. Failing in an attempt to escape to France, he was executed under the original sentence of treason passed many years before.

Raleigh was the author of a number of political essays and philosophical treatises, and of a body of poetry that was highly praised by his contemporaries. In particular he wrote a poem in reply to Christopher Marlow's famousThe Passionate Shepherd to his Love.