He wrote books on a wide range of subjects including mathematics and astronomy, English history, geography and life.
About 1838, Mudie moved to Winchester, where he was employed by a bookseller named Robbins in writing books, including a History of Hampshire (3 vols., 1838) and a stream of other topographical volumes.
He edited The Surveyor, Engineer and Architect, a monthly journal; it began publication in February 1840 but was not a financial success.
Mudie became a keen ornithologist and published several volumes, such as The Feathered Tribes of the British Islands (2 vols., 1834) and The Natural History of Birds (1834); he also wrote on other aspects of biology.
Mudie wrote the greater part of the natural history section of the British Cyclopaedia (1834), the text to Gilbert's Modern Atlas of the Earth (1840), and a topographical account of Selborne prefixed to Gilbert White's Natural History of Selborne (new edn, 1850).
He wrote and compiled altogether about 90 volumes according to the Cyclopædia of English Literature (1844),[3] including Babylon the Great – A Picture of Men and Things in London; Modern Athens, a sketch of Edinburgh society; The British Naturalist; The Feathered Tribes of Great Britain; A Popular Guide to the Observation of Nature; two series of four volumes each, entitled The Heavens, the Earth, the Sea, and the Air; and Spring, Summer, Autumn, and Winter; Man: Physical, Moral, Social, and Intellectual; Man, as a Moral and Accountable Being; The World Described; The Picture of Australia.
He also wrote a novel, Glenfergus (1820), considered by Andrew Murray Scott to bear comparison with the gentle social satires of his Ayrshire contemporary, John Galt.
[4] He furnished the letter-press to Gilbert's Modern Atlas, the "Natural History" to the British Cyclopaedia, and numerous other contributions to periodical works.