Thomas Hemerken was born around 1380 in Kempen, near Cologne. At about twelve he entered the school conducted by the Brethren of the Common Life at Deventer, an educational community devoted to the Devotio Moderna — a movement emphasizing interior piety, practical charity, and direct engagement with Scripture over scholastic disputation.

In 1399, Thomas entered the Augustinian monastery at Mount St Agnes near Zwolle, where he was ordained priest in 1413. He remained there for the next fifty-eight years, engaged in copying manuscripts, spiritual direction, and writing. His literary output included the four books of The Imitation of Christ (c. 1418–1427), biographies of community founders Gerard Groote and Florentius Radewijns, sermons, and devotional meditations.

The Imitation of Christ became the most influential devotional work of the post-medieval period, translated into every European language. Its attribution was debated for centuries (candidates included Groote and Jean Gerson), but modern scholarship firmly assigns it to Thomas. The work's emphasis on interior devotion, detachment from worldly honor, and meditation on Christ's suffering made it appealing across Catholic, Protestant, and Anglican traditions. Thomas died at Mount St Agnes in 1471 at approximately ninety-one years of age.

Thomas developed no hagiographic tradition in the medieval sense. His influence was exercised entirely through The Imitation of Christ rather than through miracle traditions or cult veneration. He was never formally canonized.