Allen, Harrison & Co Ltd was a Mancunian engineering business known to have been active between 1862 and 1939. It was founded by partners James Allen (1824-1864) and William Arthur Harrison (c1829-1884), both engineers. Allen specialised in brass fittings of engines and boilers, dedicating his career to their improvement.

In 1862 Allen, Harrison & Co was describing itself first and foremost as hydraulic and brewers' engineers. The company was based in Cambridge Street, later moving to Knott Mill in Commercial Street. During the First World War the company was involved in munitions work at Knott Mill.