There is much evidence of Macroom's pre-Christian habitation in the many standing stones, dolmens, stone circles and fulacht fiadh in the surrounding land. The area was a pre-Christian center for Bardic conventions and acted as a base for the Druids of Munster.
The first recorded historical reference to Macroom dates back to the sixth century when the townland was known as Achad Dorbchon, and held within the kingdom of Muscraighe Mitine. The dominate clan within Munster during this period was the Eoghanach dynasty, and they held kingdoms from Muscraighe Mitine to the midlands town of Birr. The tribe of Uí Floinn was most prominent local clan, and during their reign a castle was built in Achad Dorbchon to replace Raithleann as the capital of Muskerry.
In 978 a major battle was fought at Bealick between Brian Boru and the King of Carbery. The battle was the climax of a power-struggle between the Lords of Carbery and the Dál gCais of North Munster. Boru sought to avenge the slaughter of his brother Mahon, as well as to acede to the throne of Munster. Mahon had been killed by the Viking chieftain Molloy in Aghina parish a year earlier. The battle lasted a full day, during which time the battle line shifted west to Sliabh Caoin (Sleveen). It has been described as one of the "Fiercest engagements ever fought in Muskerry".
Muscraighe Mitine underwent three invasions during the thirteenth century; from the Murcheatach Uí Briain and Richard de Cogan in 1201 and 1207 respectively, and finally from the McCarthy family who had become the dominant and most powerful family in what was then known as Muscraighe Uí Fhloinn. The McCarthy family occupied the castle from this time up until the middle of the seventeenth century. By the fourteenth century Achad Dorbchon was accepted to be the capital of the Barony of Muskerry, and was seen as growing center for trade, burial and religious worship.
Macroom was one of the earliest centres in Ireland where milling was carried out. By the end of the sixteenth century, the town began to grow from a village settlement to a functionally diverse urban centre. The locality grew outwards from the castle. The McCarthys established the town as a centre for markets and fairs, and in 1620 a market house was built to the east of and facing the castle. The family introduced a plantation scheme which aimed to attract new agriculture and industrial techniques and methods to the area. By the mid-seventeenth century English families owned approximately one-third of the town in value terms. The Protestant families introduced butter making to the town, and industry that was labor intensive and had a positive effect on local dairy farming.
The battle of Macroom took place near the town in 1650, during the Cromwellian conquest of Ireland. Bishop Boetius McEgan, fighting on behalf of the McCarthys failed to hold the Castle, and he was taken prisoner by the Cromwellian forces and hanged at Carrigadrohid.
A 1750 tenement list shows the town at that time to comprised 134 buildings and 300 families, with a population ratio of 6 to 1 between Catholic and Protestants. By now the town had developed from a locality of mud cabins in the early 1660s to a linear shaped urban settlement comprised mainly of thatched cabins, replaced in due course by solid cottages through efforts of the Irish Land and Labour Association (ILLA) founded in 1894.
During the Irish War of Independence (1919-1921), Macroom was the base in Cork for the British Auxiliary Division. At the Kilmichael Ambush, 17 Auxiliaries were killed on the road between Macroom and Dunmanway by the local Irish Republican Army under Tom Barry. Macroom castle was burned out on five separate occasions; the last occasion was on 18 August, 1922 following the evacuation of British Auxiliaries from the town. The anti-treaty forces, including Erskine Childers and Frank O'Connor, had retreated from Cork City to Macroom. They burned the castle before retreating west. In 1924 the Castle and estate was gifted to the town by Lady Ardilaun. Michael Collins was killed in 1922 in an ambush near Béal na mBláth.
1.5km south of Macroom is the Gearagh, a national nature reserve which comprises an inland delta, made up of a series of small islands, separated by anastomosing river channels. The area is thought to have been wooded since the end of the last Ice Age (c. 10,000 years ago). The alluvial woodland had extended as far as the Lee Bridge, however in 1954 the Lee hydro-electric scheme was undertaken which led to extensive tree-felling and flooding in the area. The scheme resulted in the loss of sixty per-cent of the former oak woodland. Today, the Gearagh is of great natural importance due to its rich and rare diversity of wildlife, and represents the only extant extensive alluvial woodland in Western Europe.
Coláiste De La Salle was opened in 1933 was originally located in the town hall, until the permanent building was completed three years later. By the late 1970s the school was experiencing sever capacity issues and a re-structure and extension of the school was undertaken in 1982. Since its opening the ratio of puplis has remained relatively stable with 40% from coming the town and 60% from the surrounding parishes. The Convent of Mercy Secondary School is contained within the Sisters of Mercy's complex attached to St. Colmans church, which also included a convent, a primary school a graveyard and a grotto. The technical college is named after Bishop McEgan.
Aghina National School is a rurally based, two teacher, primary school within the parish of Macroom. Located 5 km from the town, it is the only co-educational primary school within the parish.
Currently a new school is being built for St Colmans Boys National School after years of appealing and applications. The new school will consist of two stories, will have wheelchair accessibility, and will have in indoor gym. The old school is planned to be knocked down during the summer holidays and the new school is planned to be opened in November 2008.
The Beaver Scouts (6 to 8 year olds) are currently not active.