The name is Old Norse in origin and is derived from Ormres kirkja, from a personal name, Ormr (which means "serpent" or dragon), and the Old Norse word kirkja for church. Ormr may have been a Viking who settled here, became a Christian and founded the church but there are no other records or archaeological evidence to support this and Ormr's identity is unknown.
There is no reference to Ormskirk in the Domesday Book of 1086, but it has been suggested that it may have been part of Lathom at that time. In about 1189, the lord of Lathom granted the church of Ormskirk to Burscough Priory, which does suggest that Ormskirk had been subordinate to Lathom before that date.
An open market is held twice weekly, on Thursdays and Saturdays, in the pedestrianised centre of Ormskirk. The location was originally the junction of the main roads to Preston, Liverpool and Wigan, and was marked by a market cross going back to medieval times. During the 18th and 19th centuries the Cross, as the junction was known, was the location of a large lamp mounted on an obelisk with a circular drinking fountain for both people and animals around the base. This was moved to the junction of St Helens Road and Moor Street to make room for the erection of the clock tower in 1876.
The fountain was then moved again to opposite the Drill Hall down Southport Road in the 1890s when space was needed to site the Disraeli statue. The market was established by a royal charter that was granted by Edward I in 1286 to the monks of Burscough Priory. Thursday has been market day in Ormskirk since at least 1292. The King also granted a borough charter to Ormskirk at about the same time, but this seems to have become extinct by the end of the 15th century.
The Ormskirk Poor Law Union was established in 1837, covering 21 parishes and townships from Tarleton to Simonswood, and from Birkdale to Skelmersdale. Ormskirk Union Workhouse was built in 1853 on Wigan Road and later became Ormskirk and District General Hospital.
With its weekly markets, the town became a focal point for local farmers and their agricultural workers, cottagers, cow-keepers etc. to trade their goods and obtain necessities from the markets and from the retail establishments which were established along with public houses and inns. An engineering industry, based on making and mending agricultural machinery also developed.
The town became known for its gingerbread over the years when local women would bake the gingerbread in their own homes and then take it to the staging inns to sell to passengers. When the railway arrived in the mid 19th century, the local gingerbread sellers found a new market. They were allowed to sell their product to passengers travelling through the railway station. One particular customer Edward, Prince of Wales, later Edward VII, enjoyed the local gingerbread so much he sent orders to the town. The baking of gingerbread became part of the retail history of the town, with several local bakers claiming to have the original gingerbread recipe. A well known local woman, Sally Woods, was a recognisable figure on the market selling her gingerbread.