Keble's early intellectual development was shaped by study of the classical writers, by deep reading in patristic theology, and by the kind of thoughtful Anglican piety that characterized the best of nineteenth-century churchmanship. In 1815, at the age of twenty-three, he won the Newdigate Prize for poetry with a work on "Christian Antiquity," demonstrating both his poetic gift and his deep engagement with the early church. He was ordained to the priesthood in 1815 and served as a Fellow and tutor at Oriel College while developing his scholarly and literary output.

In 1827, Keble published The Christian Year: Thoughts in Verse for the Sundays and Holy Days throughout the Year. This was a collection of poems, one or more for each Sunday and feast day of the Christian calendar, designed to accompany the Book of Common Prayer and to deepen believers' spiritual reflection on the liturgical year. The work was immediately successful and became, astonishingly, the second-best-selling poetry collection in Victorian England (second only to Tennyson's collected works). That such a work of explicitly Christian devotional poetry should achieve such popular success is a measure of its spiritual power and accessibility. The poems combine theological depth with emotional immediacy, classical formal restraint with genuine spiritual fervor. They shaped the piety of Victorian Anglicanism, teaching believers to see the church calendar as a comprehensive school of Christian virtue.

Through his professorship at Oxford (he was appointed Professor of Poetry in 1831, a position he held for ten years), Keble exercised wide influence on the intellectual life of the university and the broader church. His lectures on poetry and on sacred texts demonstrated that classical learning and spiritual depth could interpenetrate—that serious scholarship was not opposed to genuine faith.

The defining moment of Keble's public life came on July 14, 1833, when he preached the Assize Sermon at Oxford. The sermon, titled "National Apostasy," was a fierce denunciation of what Keble perceived as the Church of England's willingness to compromise its apostolic independence and integrity by accepting political interference from a secular Parliament. The sermon was occasioned by the government's decision to suppress ten Anglican bishoprics in Ireland—a decision that Keble saw as unwarranted state interference in ecclesiastical affairs. But the sermon's significance extended far beyond its immediate occasion: it articulated a comprehensive vision of the church as a divinely ordered institution, rooted in apostolic succession, grounded in patristic theology, and responsible to Christ (not to Parliament) for its doctrine and discipline.

The Assize Sermon sparked a movement. Within days, Keble and his colleagues at Oxford, most notably John Henry Newman and Edward Bouverie Pusey, began publishing a series of Tracts for the Times—theological and devotional essays designed to recover what they saw as the apostolic and patristic character of the Church of England and to awaken English Anglicans to a deeper understanding of their ecclesiastical inheritance. Keble contributed to the Tracts and was a key leader of the movement, though he was less prolific and less theologically systematic than Newman or Pusey. His role was more one of spiritual inspiration and poetic articulation.

Keble's scholarly and pastoral work was continuous and fruitful. He edited the works of Richard Hooker, the great Elizabethan theologian, making Hooker's thought available to a new generation. He wrote biblical and theological commentaries. He maintained an extensive pastoral correspondence with friends and believers who sought his spiritual guidance. In 1836, while continuing his scholarly work, he accepted the modest rural living of Hursley in Hampshire, where he served as the village vicar until his death in 1866. He lived simply and devotedly, his parishioners regarding him with great affection and respect.

The Oxford Movement, which Keble helped launch, eventually transformed the spiritual life of the Church of England, despite fierce opposition from evangelical and liberal factions. Its emphasis on apostolic succession, sacramental theology, liturgical beauty, and patristic learning became normative in the Anglican Church and influenced Protestant and even some Roman Catholic theology. Newman and others eventually moved toward Rome, a development that troubled Keble deeply; but Keble himself remained a committed Anglican, believing that the church of his baptism could and should be reformed from within by a recovery of its own deepest traditions.

Keble died on March 29, 1866, at the age of seventy-three, having been the living spirit of the Oxford Movement for more than three decades. The movement itself outlasted him and continues to influence Anglican theology and practice today.