Warton was born in Basingstoke, Hampshire, the son of poet Thomas Warton, the Elder, and younger brother of Joseph Warton. As a youngster, Warton demonstrated a strong predilection toward writing poetry, a skill he would continue to develop all of his life. In fact, Warton translated one of Martial's epigrams at nine, and wrote The Pleasures of Melancholy at seventeen.

His early education was given him by his father. At sixteen years of age he enrolled at Winchester College, later moving to Trinity College, Oxford. He graduated from Oxford in 1747, where he subsequently became a Fellow. Warton was selected as Poet Laureate of Oxford in 1747 and again in 1748. His duty in this post was to write a poem about a selected patroness of the University, which would be read to her on a specially appointed day. Warton was appointed Professor of Poetry at the university in 1757, a post that he held for ten years.

In 1771 he was appointed rector of Kiddington in Oxfordshire, a post he held until his death.

In 1785, he was appointed Camden Professor of History, as well as poet laureate. He was a friend and rival of Samuel Johnson, and his poetry was greatly influenced by earlier English poets such as Chaucer, Drayton, Fairfax, and Spenser.

Among other important contributions, Warton, along with his brother, was among the first to argue that Sir Thopas, by Geoffrey Chaucer, was a parody. Warton contributed to the general project of the ballad revival. He was a general supporter of the poetry of Thomas Gray — a fact that Johnson satirized in his parody "Hermit hoar, in solemn cell." Among his minor works were an edition of Theocritus, a selection of Latin and Greek inscriptions, the humorous Oxford Companion to the Guide and Guide to the Companion (1762); lives of Sir Thomas Pope and Ralph Bathurst; and an Inquiry into the Authenticity of the Poems attributed to Thomas Rowley (1782).

In 1749, Warton penned The Triumph of Isis, a poem in praise of Oxford and the many students who had received their education there. Published anonymously, The Triumph of Isis rebutted William Mason’s Isis, an Elegy published the previous year, which was anything but flattering to Oxford.

Following the success of The Triumph of Isis, Warton wrote Newmarket, a Satire, which was followed by a collection of verses. His complete poetical works were included in an anthology that has been reissued.

Warton's first major academic work was Observations on the Faerie Queene of Spenser, published in 1754. He is, however, best known for the three volume The History of English Poetry (1774 – 81), which covered the poetry of the 11th through the 16th centuries. Although the work was criticized for its many inaccuracies, it is nonetheless considered a highly important and influential historical tome.

In 1782 he wrote The History and Antiquities of Kiddington, an early example of English local history.

As a poet, Warton was more inclined toward light and humorous verse, odes and sonnets. His sonnets helped to revive the form, which had fallen out of fashion.

He is remembered for his interest in primitivism, which was an important stage toward romanticism.

To the River Lodon

Ah! what a weary race my feet have run Since first I trod thy banks with alders crowned, And thought my way was all thro' fairy ground, Beneath thy azure sky and golden sun; Where first my muse to lisp her notes begun! While pensive Memory traces back the round, Which fills the varied interval between; Much pleasure, more of sorrow, marks the scene. Sweet native stream! those skies and suns so pure No more return, to cheer my evening road! Yet still one joy remains, that, not obscure, Nor useless, all my vacant days have flowed, From youth's gay dawn to manhood's prime mature; Nor with the muse's laurel unbestowed.