Almost everything securely known about Chrétien comes from his own works. His name points to Troyes in Champagne, and his writing shows the education expected of a sophisticated twelfth-century poet, but his social status, travels and career cannot be reconstructed with certainty. The five surviving Arthurian romances are the firm ground: Erec and Enide, Cligés, Lancelot or The Knight of the Cart, Yvain or The Knight with the Lion, and Perceval or The Story of the Grail. Two prologues also identify patrons, giving rare documentary anchors for an otherwise elusive life.

His first surviving Arthurian romance, Erec and Enide, begins with King Arthur, the legendary British king, holding Easter court at Cardigan. A white stag hunt launches a dispute over the fairest lady, while Erec follows an insulted maiden through a forest of adventures and wins Enide, the daughter of a poor vavasor. Their marriage then faces the harder question of what a knight owes his wife and his fame after the wedding. Chrétien binds the episodes into a single design, proving that scattered marvels can become a coherent story about love, shame, and reconciliation.

Cligés leaves Britain for the Byzantine world. The hero, son of a Greek emperor's daughter and a Greek knight, falls in love with Fenice, his uncle's wife. Fenice refuses to become another Isolde and escapes a forced marriage through a potion that imitates death. The romance gleams with Ovid, the classical poet of love and transformation, and turns the fatal adultery of Tristan into a tale of escape, cunning, and survival. Chrétien is already testing the rules of courtly love rather than merely repeating them.

At the court of Marie, Countess of Champagne, daughter of Eleanor of Aquitaine, Chrétien receives a commission that changes Arthurian literature. Marie gives him the matiere and san of Lancelot, the subject and governing idea of the romance. Lancelot, Arthur's greatest knight, rides in shameful rescue of Queen Guinevere, Arthur's wife, who has been carried away by the wicked knight Meleagant. Even the cart of criminals cannot stop him, because his devotion to the queen outranks his fear of dishonour. Godefroi de Leigni, another poet, completes the ending with Chrétien's approval. Around the same time Chrétien writes Yvain, the Knight of the Lion, in which Yvain marries Laudine, the Lady of the Fountain, breaks his promise to return, loses his mind, regains himself through service, and comes back as the knight with a lion at his side.

His final romance, Perceval, turns from courtly adventure toward sacred mystery. Philip of Flanders gives Chrétien a book as the source, and from it the poet shapes the story of an innocent Welsh boy who becomes a knight, reaches the castle of the wounded Fisher King, and watches a procession with a bleeding lance and a shining vessel, the Grail, pass before him. Perceval fails to ask the question that would heal the king. Chrétien leaves the work unfinished, and later poets continue the tale until the Grail quest becomes one of the great structures of European literature.

Chrétien's influence moved quickly across languages. Hartmann von Aue adapted Erec and Yvain in German, and Wolfram von Eschenbach transformed the unfinished Perceval into Parzival. French prose writers later absorbed characters and themes associated with Chrétien into the great Arthurian cycles, and those traditions in turn fed the English Arthurian world of Thomas Malory. The cart of shame, the Knight of the Lion, the wounded Fisher King and the Grail procession all became durable parts of European Arthurian storytelling. What happened to Chrétien himself after the unfinished Perceval is uncertain; later testimony says death prevented him from completing it.