Her main armament consisted of four breech-loading (BL) 7.5-inch Mk I guns mounted in four single-gun turrets, one each fore and aft of the superstructure and one on each side. The guns fired their shells to a range of about . Her secondary armament of six BL 6-inch Mk VII guns was arranged in casemates amidships. Four of these were mounted on the main deck and were only usable in calm weather. They had a maximum range of approximately with their shells. "Argyll" also carried 18 quick-firing (QF) 3-pounder Hotchkiss guns and two submerged 18-inch torpedo tubes. Her two 12-pounder 8 cwt guns could be dismounted for service ashore.