Coventry Ordnance Works was a British manufacturer of heavy guns particularly naval artillery jointly owned by Cammell Laird & Co of Sheffield and Birkenhead, Fairfield Shipbuilding and Engineering Company of Govan, Glasgow and John Brown & Company of Clydebank and Sheffield. Its core operations were from a 60-acre (24 ha) site in Stoney Stanton Road in the English city of Coventry, Warwickshire.

At the end of 1918 it became a principal constituent of a brand new enterprise English Electric Company Limited. After World War II the works made electricity-generating machinery and heavy machine tools.

The company, the Coventry Ordnance Works Limited, was formed in July 1905 by a consortium of British shipbuilding firms John Brown 50 percent, Cammell Laird 25 percent and Fairfield 25 percent with the encouragement of the British government, which wanted a third major arms consortium to compete with the duopoly of Vickers Sons & Maxim and Sir W G Armstrong Whitworth & Co to drive down prices. The new company bought (as from 1 January 1905, six months earlier) from Cammell Laird the ordnance business established in the late 1890s by H H Mulliner and F Wigley which had been moved by them in 1902 from Birmingham to the 60-acre (24 ha) site in Coventry's Stoney Stanton Road. The ordnance business had been bought from Mulliner and Wigley by Charles Cammell, later Cammell Laird, in 1903.

By 1909 Coventry Ordnance Works had establishments, as well as at Coventry, at Scotstoun for manufacture of ordnance and gun equipment; for cordite shell loading and explosive magazines at Cliffe; and a gun-proving ground with a land range of 22,000 yards at Boston and was handling an order for 12 inch mountings of one of the new battleships. While to that time the works had been manufacturing the smaller sizes of Naval Guns and Mountings as well as Guns, Gun carriages, Ammunition and other military accessories, they had already extended their works since 1906 and had begun the manufacture of Guns and Turrets up to the largest sizes for both Battleships and Cruisers for the Admiralty. At Scotstoun a new factory had been built with a wet dock, pits and machinery for the erection and transhipping of the heaviest guns and mountings and hydraulic barbettes of the firm's own design but it was unused until 1911. A complete factory for the manufacture of Fuzes had also been installed in Coventry.

To this point Herbert Hall Mulliner (1861–1924) had continued as managing director, but after a long series of altercations with the Admiralty he was asked to resign, compensated, and replaced 3 February 1910 by the 46-year-old rear-admiral R. H. S. Bacon who had been the Admiralty's Director of Naval Ordnance since August 1907. By early February with admiral Bacon on board and Mulliner off it the directors could report an order from the British Admiralty for the mountings of all the heavy guns of one of the latest battleships that brought into operation for the first time the most costly and most important part of the company's new plant ending a long difficult period for Coventry Ordnance Works. Early in 1915 Bacon was appointed to the Royal Marines.

Coventry Ordnance Works designed and built:

At their Annual General Meeting four days after the armistice Dick, Kerr & Co Limited announced a provisional agreement for amalgamation with Coventry Ordnance Works Limited. Subsequently English Electric Company Limited was formed at the end of 1918 to own all the shares of Coventry Ordnance Works, Phoenix Dynamo Manufacturing Company and Dick Kerr & Co together with the United Electric Car Company and Willans & Robinson. It was anticipated that the new combine would be one of the three principal electrical manufacturing concerns in the country. It was intended that its business would be in large schemes such as the electrification of railways, the construction of large central power stations and the development of hydro-electric installations.

It struggled in the recession after the end of World War I which affected Britain's arms industry and closed in 1925.