His writings include an introduction to Henry Merritt: Art Criticism and Romance, published in 1879 and Churches about Queen Victoria Street, a portfolio published in 1871, Victorian art and originality for the British Architect published in 1887, and The architecture of Queen Victoria's reign for the Art Journal, published in 1887. A Quiet Corner of England: Studies of Landscape and Architecture in Winchelsea, Rye and Romney Marsh was published in 1875 after being circulated as a portfolio and a work regarding his mother-in-law, Adelaide Drummond, A Retrospect and Memoir, was published in 1915. Champneys' correspondence has been preserved in the General Collection of the Beinecke Rare Book and Manuscript Library.
Architecture
Believing that architecture was 'an art not a science' he joined the Art Workers Guild instead of the Royal Institute of British Architects. Although Champneys was able to work in the Gothic style that John Prichard preferred and taught, he later became one of the pioneers of the Queen Anne style, working on at least 100 buildings throughout England. John Rylands' widow, Enriqueta Rylands, had admired the library Champneys had designed for Mansfield College, Oxford and hired him to develop the design on a more lavish scale – The John Rylands Memorial Library in Deansgate, Manchester took nine years to build before opening on 1 January 1900, it is one of Champneys' finest designs. Champneys' Oxford buildings include the Church of St Peter-le-Bailey, which serves as the chapel for St Peter's College, New Old Hall in Lady Margaret Hall, the Indian Institute, the Mansfield College library, the Robinson Tower at New College, the Somerville College Library, the St. Alban Hall buildings at Merton College, a chapel and residence hall at Linacre College, the Rhodes Building in Oriel College. His Cambridge works include the Archaeological Museum, now Peterhouse Theatre, the Divinity and Literary School and Newnham College, for which he is credited for bringing a 'touch of lightness' to the college and is acknowledged for his attention to both construction details, and to cost. Champneys' buildings elsewhere include the chapel of Mill Hill School, London, buildings for Bedford College in Regent's Park, King Edward VII School , the Butler Museum at Harrow School, the museum at Winchester College, and Bedford High School. Champneys also designed the Wilnecote Board School buildings as a slightly earlier work in 1877; this building is in danger of demolition due to Staffordshire County Council wishing to give the land away to a land developer. Churches by Champneys include his father's parish church, St Luke's, Kentish Town, the sailors' church of St Mary Star of the Sea, Hastings, and St Chad, Slindon, Staffordshire. In 1897 he did the painting of clouds, cherubs and scrolls on the ceiling of St George the Martyr Southwark in London. In 1898 he added a porch to St Mary, Manchester, where he was surveyor, and between 1902 and 1903, a south annexe. His home, Hall Oak, in Frognal, Hampstead was also one of his works.