Royle succeeded John Ayrton Paris in 1836 as professor of materia medica at King's College London, a position he held till 1856. He became a fellow of the Linnean Society in 1833 and the Royal Society in 1837. He made use of his collections to publish his "Illustrations of the botany and other branches of the natural history of the Himalayan mountains" (2 vols., 1839). In this work he suggested the introduction of cinchona to India stating that in "the Neelgherries a favourable site might without doubt be found for the cinchona". In 1851 he superintended the Indian department of the Great Exhibition. In 1852, his recommendation for the introduction of cinchona was approved by the Lord Dalhousie, governor-general of India. Royle produced a report on this in 1853 but work began only in 1860, two years after Royle's death at Acton near London on 2 January 1858.