Before William Shakespeare, Geoffrey Chaucer was the preeminent English poet, and still retains the position as the most significant poet to write in Middle English. Chaucer was born in the early 1340s to a middle-class family. His father, John Chaucer, was a vintner and deputy to the king's butler. His family's financial success came from work in the wine and leather businesses. Little information exists about Chaucer's education, but his writings demonstrate a close familiarity with a number of important books of his contemporaries and of earlier times. Chaucer was likely fluent in several languages, including French, Italian and Latin.

Chaucer first appears in public records in 1357 as a member of the house of Elizabeth, Countess of Ulster. This was a conventional arrangement in which sons of middle-class households were placed in royal service so that they may obtain a courtly education. Two years later Chaucer served in the army under Edward II and was captured during an unsuccessful offensive at Reims, although he was later ransomed. Chaucer served under a number of diplomatic missions. By 1366 Chaucer had married Philippa Pan, who had been in service with the Countess of Ulster. Chaucer married well for his position, for Philippa Chaucer received an annuity from the queen consort of Edward II. Chaucer himself secured an annuity as yeoman of the king and was listed as one of the king's esquires.

Chaucer's first published work was The Book of the Duchess, a poem of over 1,300 lines that is an elegy for the Duchess of Lancaster. For this first of his important poems, which was published in 1370, Chaucer used the dream-vision form, a genre made popular by the highly influential 13th-century French poem of courtly love, the Roman de la Rose, which Chaucer translated into English. Throughout the following decade, Chaucer continued with his diplomatic career, traveling to Italy for negotiations to open a Genoa port to Britain as well as military negotiations with Milan. During his missions to Italy, Chaucer encountered the work of Dante, Petrarch, and Boccaccio, which were later to have profound influence upon his own writing. In 1374 Chaucer was appointed comptroller of the customs and subsidy of wool, skins, and tanned hides for the Port of London, his first position away from the British court. Chaucer's only major work during this period was Hous of Fame, a poem of around 2,000 lines in dream-vision form, but this was not completed.

In a deed of May 1, 1380, Cecily Chaumpaigne charged Chaucer with rape. Rape (raptus) could at the time mean either sexual assault or abduction; scholars have not been able to establish which meaning applies here, but, in either case, the release suggests that Chaucer was not guilty as charged. This charge had little effect on Chaucer's political career. In October 1385, he was appointed a justice of the peace for Kent, and in August 1386 he became knight of the shire for Kent. Around the time of his wife's death in 1387, Chaucer moved to Greenwich and later to Kent. Changing political circumstances eventually led to Chaucer falling out of favor with the royal court and leaving Parliament, but when Richard II became King of England, Chaucer regained royal favor. During this period Chaucer used writing primarily as an escape from public life. His works included Parlement of Foules, a poem of 699 lines. This work is a dream-vision for St. Valentine's Day that makes use of the myth that each year on that day the birds gathered before the goddess Nature to choose their mates. This work was heavily influenced by Boccaccio and Dante.

Chaucer's next work was Troilus and Criseyde, which was influenced by The Consolation of Philosophy, written by the Roman philosopher Boethius in the early sixth century and translated into English by Chaucer. Chaucer took the plot of Troilus from Boccaccio's Filostrato. This eight thousand line poem recounts the love story of Troilus, son of the Trojan king Priam, and Criseyde, widowed daughter of the deserter priest Calkas, against the background of the Trojan War.

The Canterbury Tales secured Chaucer's literary reputation. It is his great literary accomplishment, a compendium of stories by pilgrims traveling to the shrine of Thomas a Becket in Canterbury. Chaucer introduces each of these pilgrims in vivid brief sketches in the General Prologue and intersperses the twenty-four tales with short dramatic scenes with lively exchanges. Chaucer did not complete the full plan for the tales, and surviving manuscripts leave some doubt as to the exact order of the tales that remain. However, the work is sufficiently complete to be considered a unified book rather than a collection of unfinished fragments. The Canterbury Tales is a lively mix of a variety of genres told by travelers from all aspects of society. Among the genres included are courtly romance, fabliau, saint's biography, allegorical tale, beast fable and medieval sermon.

Information concerning Chaucer's descendants is not fully clear. It is likely that he and Philippa had two sons and two daughters. Thomas Chaucer died in 1434; he was a large landowner and political officeholder, and his daughter, Alice, became duchess of Suffolk. Little is known about Lewis Chaucer, Geoffrey Chaucer's youngest son. Of Chaucer's two daughters, Elizabeth became a nun, while Agnes was a lady-in-waiting for the coronation of Henry IV in 1399. Public records indicate that Chaucer had no descendants living after the fifteenth century.