Living in London from 1796, Robinson practiced law as a barrister on the Norfolk circuit (1813–28). He also served as foreign correspondent for The Times of London (1807–09) and became involved in the antislavery campaign and in the founding of the University of London. He befriended William Blake, of whose last years Robinson's diaries give the fullest account. He also knew Charles Lamb, William and Dorothy Wordsworth, and Samuel Taylor Coleridge, of whose lectures he made notes. In Germany (1800–05) he met the leading poets and thinkers of his day, including J.W. von Goethe, Friedrich von Schiller, and J.G. von Herder; on his return to England, he was influential in making German literature and philosophy more widely known.

His diaries were first published in 1869. Collections of his correspondence with the Wordsworth circle (1927), about Germany (1929), and about books and writers (1938) were edited by E.J. Morley.