After he returned from Italy Flaxman devoted himself almost exclusively to monuments, two of his most famous having been begun in Rome. These are the Mansfield, erected in Westminster Abbey in 1795, and the Collins of the same year in Chichester Cathedral, and the Agnes Cromwell of 1800, also in Chichester Cathedral (model in University Coll. London). While still in Rome he had also begun the book-illustrations which brought him the greatest fame on the Continent and influenced later generations - Ingres and the Nazarener among them. These are pure outline drawings of strictly Neoclassical simplicity, which give the impression of being sketches for relief sculpture: they include long series of plates for the Odyssey and the Iliad, Aeschylus, Hesiod, Dante, as well as Milton and Bunyan drawings.

He became an RA in 1800 and was made Professor of Sculpture in 1810, his lectures being published posthumously in 1829. Among his few statues in the round which are not monuments are the Fury of Athamas (1791-92: NT, Ickworth House) and St Michael Overcoming Satan (1821) and the Pastoral Apollo (1824: both NT, Petworth). University Coll., London, has a large collection of his drawings and models, and the Soane Mus., London, also has models. Other works are scattered as far as Madras and Quebec and include works in Bath, many in Chichester Cath., Copenhagen, Edinburgh (NPG), Glasgow, Gloucester, London (NPG, V&A, RA, Westminster Abbey, St Paul's), and many other English churches and cathedrals.