John Walker (1787 - April 19, 1873) was a British mapseller, engraver, lithographer, hydrographer, geographer, draughtsman and publisher active in London during the 19th century. Walker published both nautical charts and geographical maps. His nautical work is particular distinguished as he was an official hydrographer for the British East India Company, a position, incidentally, also held by his father of the same name. Walker's maps mostly published after 1827, were primarily produced in partnership with his brother Charles Walker under the imprint J. and C. Walker. Among their joint projects are more than 200 maps for the influential Society for the Diffusion of Useful Knowledge Atlas (SDUK). In addition they published numerous charts for James Horsburgh and the British Admiralty Hydrographic Office, including Belcher's important map of Hong Kong and Carless' exploratory map of Karachi. The J. and C. Walker firm continued to publish after both Walkers died in the 1870s.