She was armed with four 12-inch guns arranged in two twin gun turrets, one turret each fore and aft. Her secondary armament consisted of ten 9.2-inch (234 mm) guns, eight in twin gun turrets on each corner of the superstructure, and a single gun turret between them. For defence against torpedo boats, "Lord Nelson" carried twenty-four QF 12-pounder 18 cwt guns and two 3-pounder guns. She also mounted five submerged 18-inch (457 mm) torpedo tubes for which 23 torpedoes were stowed aboard.