Irlam was anciently known as Irwellham, an outlying area of Chat Moss, a large peat bog which straddled the River Irwell. Work was carried out in the 19th century to reclaim large areas to enable the completion of the Liverpool and Manchester Railway in 1829. In 1894, the Irwell was adjusted so that its waters were united with the Manchester Ship Canal, stimulating the growth of Irlam as an inland port. Irlam Urban District was established in the same year and was governed thereafter by its own district council until its abolition in 1974.
Irlam's geography is varied: the northern half is still moss land, with a large farming community; the southern half is predominantly residential.
Irlam is on the north bank of the River Irwell, from which it almost certainly takes its name, being known in the 13th century as Irwellham. Until the arrival of the Cheshire Lines Committee railway and the opening of Irlam railway station in 1873, Irlam remained a largely undeveloped village, on the southern edge of the peat bog known as Chat Moss.
From at least the beginning of the 13th century, Irlam was held by the Irlam family, whose seat was Irlam Hall. By 1688 Irlam Hall had become the home of Thomas Latham, who played an important part in bringing William of Orange to the throne of England in 1689.
Irlam Urban District was created in 1894, the same year that the Manchester Ship Canal opened. A pair of locks and a ship coaling berth were constructed here. The subsequent industrial development of Irlam owed much to the construction of the canal, which effectively rendered the River Irwell navigable to large ocean-going ships up to Manchester Docks. The Latham family's importance to the local area was acknowledged when their features were incorporated into the arms of Irlam's former urban district council.