Beyond the fact that he was of Anglo-Saxon, not of Norman extraction, and applied to himself the cognomen of Parvus, "short," or "small," few details are known regarding his early life; but from his own statements it is gathered that he crossed to France about 1136, and began regular studies in Paris under Pierre Abélard, who had there for a brief period re-opened his famous school on Montagne Sainte-Geneviève.

After Abelard's retirement, John carried on his studies under Alberich of Reims and Robert of Melun. From 1138 to 1140 he studied grammar and the classics under William of Conches and Richard l'Evêque, the disciples of Bernard of Chartres, perhaps at Chartres.

Bernard's teaching was distinguished partly by its pronounced Platonic tendency, partly by the stress laid upon literary study of the greater Latin writers. The influence of the latter feature is noticeable in all John of Salisbury's works.

About 1140 he was at Paris studying theology under Gilbert de la Porrée, then under Robert Pullus and Simon of Poissy. In 1148 he resided at Moutiers la Celle in the diocese of Troyes, with his friend Peter of Celle. He was present at the council of Reims, presided over by Pope Eugene III, and was probably presented by Bernard of Clairvaux to Theobald, archbishop of Canterbury, under whose sponsorship he returned to England about 1150.

Appointed secretary to Theobald, he was frequently sent on missions to the papal see. During this time he composed his greatest works, published almost certainly in 1159, the Policraticus, sive de nugis curialium et de vestigiis philosophorum and the Metalogicon, writings invaluable as storehouses of information regarding the matter and form of scholastic education, and remarkable for their cultivated style and humanist tendency. The phrase Standing on the shoulders of giants is attributed to this work. The Policraticus also sheds light on the decadence of the 12th century court manners and the ethical lowness of the royalty. After the death of Theobald in 1161, John continued as secretary to Thomas Becket, and took an active part in the long disputes between that primate and his sovereign, Henry II.

His letters throw light on the constitutional struggle then agitating England. With Becket he withdrew to France during the king's displeasure; he returned with him in 1170, and was in Canterbury at the time of Becket's assassination. In the following years, during which he continued in an influential situation in Canterbury, but at what precise date is unknown, he wrote a Life of Becket.

In 1176 he was made bishop of Chartres, where he passed the remainder of his life. In 1179 he took an active part in the third Lateran council. He died at or near Chartres on October 25, 1180.

John's writings are excellent at clarifying the literary and scientific position of 12th century Western Europe. His views imply a cultivated intelligence well versed in practical affairs, opposing to the extremes of both nominalism and realism a practical common sense. His doctrine is a kind of utilitarianism, with a strong leaning on the speculative side to the modified literary scepticism of Cicero, for whom he had unbounded admiration and on whose style he based his own.

Of Greek writers he appears to have known nothing at first hand, and very little in translations. The Timaeus of Plato in the Latin version of Chalcidius was known to him as to his contemporaries and predecessors, and probably he had access to translations of the Phaedo and Meno. Of Aristotle he possessed the whole of the Organon in Latin; he is, indeed, the first of the medieval writers of note to whom the whole was known.

John was portrayed by actor Alex G. Hunter in the 1923 silent film Becket, based on a play by Alfred Lord Tennyson.

Latin text and English translations of John's works

• Anselm & Becket. Two Canterbury Saints' Lives by John of Salisbury, Ronald E. Pepin (transl.) Turnhout, 2009, Brepols Publishers,ISBN 978-0-88844-298-7
• The Letters of John of Salisbury, 2 vols., ed. and trans. W. J. Millor and H. E. Butler (Oxford: Oxford University Press, 1979-86)
• Historia Pontificalis, ed. and trans. Marjorie Chibnall (Oxford: Oxford University Press, 1986)
• John of Salisbury's Entheticus maior and minor, ed. and trans. Jan van Laarhoven [Studien und Texte zur Geistesgeschichte des Mittelalters 17] (Leiden: Brill, 1987)

English translations of John's works

• Policraticus, ed. and trans. Cary Nederman (Cambridge: Cambridge University Press, 1990)
• The statesman’s book of John of Salisbury; being the fourth, fifth, and sixth books, and selections from the seventh and eighth books, of the Policraticus, trans. John Dickinson (New York: Knopf, 1927)
• Frivolities of courtiers and footprints of philosophers, being a translation of the first, second, and third books and selections from the seventh and eighth books of the Policraticus of John of Salisbury, trans. Joseph B. Pike (Minneapolis: University of Minnesota Press, 1938)
• The Metalogicon, a twelfth-century defense of the verbal and logical arts of the trivium, trans. Daniel McGarry (Berkeley: University of California Press, 1955)

English excerpts of John's political theory

• Policraticus, IV, selections
• Policraticus, VI, 24