U-47 may refer to one of the following German submarines:
- SM U-47 (Germany), a Type U 43 submarine launched in 1915 and that served in the First World War until scuttled on 28 October 1918
- German submarine U-47 (1938), a Type VIIB submarine that served in the Second World War until she went missing after 7 March 1941
U-47 or U-XLVII may also refer to:
- SM U-47 (Austria-Hungary), a U-43 class submarine of the Austro-Hungarian Navy