The earliest records suggest that the Ironmongers, then known as Ferroners, were an effective body in 1300, when they took action against the smiths of the Wealds of Kent and Sussex over the quality of iron supplied for the wheels of carts in the City of London. By 1328 they were regarded as a firmly established brotherhood, joining in the elections of the City officials and choosing four of their members to treat with the Mayor and Sheriffs.The Ironmongers' received a grant of arms in 1455, describing them as the "Honourable Crafte and Fellasship of Fraunchised Men of Iromongers", and a charter of incorporation from Edward IV in 1463, which was reconfirmed in 1558, 1560, 1604 and 1687 by various monarchs.

The Company's arms embody various iron and steel objects, with two salamanders as a crest, mediaeval salamanders reputedly being able to survive fire. Salamanders, as supporters, were granted in 1923, although they had been used before then. The charter granted power to appoint a "Master and two Keepers or Wardens". A subsequent Act of Parliament required Companies to prepare ordinances for approval by certain of the King's officers over matters such as the preservation of trade secrets, the qualifications of members, the regulation of apprenticeships, domestic matters of the fraternity and the settlement of internal disputes.

The Company, along with others, suffered extortion under Henry VIII, Philip and Mary and Charles I, and a similar attempt in 1684 under Charles II, which called into question the validity of the charter of the City itself and those of the Livery Companies. Although the latter was halted by James II, the Company was mulcted of a considerable sum by a fine imposed by Judge Jeffrey in 1668 to redeem their charter. Since Stuart times the Livery Companies have been left in relative peace, except that they have been involved in conflict over the continued existence of the Corporation of London in the context of contemporary local government.

The relationship between the Ironmongers' Company and the iron industry was greatly affected by the sudden concentration of the smelting and founding of iron in the Midlands and north of Britain, where there were abundant supplies of iron ore and coal, so that the activities of the Company in London were reduced to the administration of charities, participation in the affairs of the City, and its own domestic affairs. In 1457 the Company bought buildings in Fenchurch Street and converted them into a Hall, which was later enlarged. It was rebuilt in 1587 and escaped the Great Fire of 1666. A third Hall was built in 1745 on the same site. In the First World War, on 7th July 1917, during a raid by about twenty German aeroplanes, it was damaged by a bomb. After the war, the site was sold and the building demolished. The land in Shaftesbury Place, Aldersgate Street, on which the present Hall stands, was bought in 1922 and the Hall was opened on 17th June 1925.

The Tudor style of the new Hall was decided upon, not only because it seemed appropriate for the housing of an ancient guild, but also because it recalled the Golden Age of Craftsmanship. The Hall had a remarkable escape in December 1940, when a German air raid set fire to all the adjacent buildings, which were destroyed. The heat melted lead pipes and glass in the windows. One further threat to the Hall was survived in 1966, when it was nearly subject to a compulsory purchase order by the City Corporation to make way for the new Museum of London. Having survived the Great Fire and serious bomb damage in the two wars, the Company has extensive records of its history. The Court books and the membership records are unbroken since 1555. Except for the charters, the Company's records prior to 1900 are on loan to and kept in the Guildhall Library of the City of London.

The Company is tenth in order of precedence and is, therefore, one of the Great Twelve Livery Companies. It has about two hundred and eighty freemen. One hundred and thirty of them are liverymen, of whom thirty eight are on the Court, and the rest are freemen.