Before the town there was a ringfort, a rath - Cogan's rath, named for Miles de Cogan, granted the lands after the Norman invasion of 1169. The Irish name Rath an Chogain (anglicized as Rathgoggan or Rathcogan) stuck to the civil parish for centuries. When Roger Boyle, 1st Earl of Orrery, founded a new town here in 1661, he had a problem. He had been one of Cromwell's strongest supporters during the English Civil War and the conquest of Ireland. Now Cromwell was dead, the monarchy was restored, and Charles II needed to be convinced that the new Earl was a loyal subject. Boyle's solution was to name his new town Charleville, after the king. It worked. The lands had been bought by Roger's father Richard Boyle, 1st Earl of Cork, during the Plantation of Munster. Roger built his residence here and set the streetplan that survives. Through the Penal Laws period in the 18th century, when Catholic worship was illegal, the parish was amalgamated with Bruree and Colmanswell, and Mass was said in secret. The old church at Holy Cross was abandoned, and you can still see its ivy-grown remains in the middle of the cemetery.

After the 1920 local elections, Sinn Fein-controlled councils across Ireland set about replacing English monarchic place names with older Gaelic ones. Charleville Rural District Council looked at the options. They could have gone back to Rathgoggan. Instead they took the advice of the Gaelic League scholar Risteard O Foghludha, writing under the pen name Fiachra Eilgeach, who recommended Rath Luirc - 'the rath of Lorc.' Lorc, he said, was an ancient king of Munster. Charleville was renamed Rathluirc in 1920. The trouble was, Loegaire Lorc was a mythical High King of Ireland, not a king of Munster, and there is no evidence the rath at Charleville had ever been associated with him. The name change held legally - Rathluirc became the town's English-language legal name, with An Rath as its Irish form - but Charleville stayed in use locally, and 'Rathluirc (Charleville)' became the awkward compromise on official documents. The town still has a rath in the crest of its sports clubs.

Whatever its name, Charleville produced an unusual number of consequential lives. Eamon de Valera, born in New York in 1882, was educated at CBS Charleville before going on to lead Ireland through the war of independence, the civil war, three terms as Taoiseach, and the presidency. Daniel Mannix, born just outside town in 1864, became Archbishop of Melbourne for 46 years and was, by most counts, the single most influential public figure in 20th-century Australia. Eliza Lynch, born locally in 1833, became the consort of Francisco Solano Lopez of Paraguay and effectively the First Lady during the disastrous Paraguayan War. Con Leahy of Charleville won Olympic medals in 1906 and 1908. Sean Clarach Mac Domhnaill, the Chief Poet of Munster, lived in the area until his death in 1754 and is buried at Holy Cross. William Reeves, born here in 1815, became Bishop of Down and Connor and President of the Royal Irish Academy. William Alcock Tully, who served as 2nd Surveyor General of Queensland, surveyed the town site of Charleville, Queensland, and named it after this one.

Charleville sits at a junction - the N20 from Cork to Limerick meets the R515 east-west road, and the Dublin-Cork main railway line passes through Charleville station, which opened in 1849. The old Cork-Limerick line branched off here too until 1976; now Limerick passengers change at Limerick Junction further north. The town's industrial life today runs through dairy (Kerry Foods, with Cheestrings and Low Low cheese spreads), through engineering (BCD, Diamond, and Sapphire Engineering, all spin-offs after Golden Vale Engineering closed in 1983), and through Charleville Plant Hire, one of Ireland's largest plant hire companies, now part of the British group VP plc. The town has two theatres, a Muay Thai club, a soccer club, a rugby club, a Camogie club, and a GAA club. The library is in the former Church of Ireland church, which fell out of use in the 1950s and 60s as the local Protestant population dwindled. The Golden Vale around it is some of the best dairy country in Europe, which is why the cheese is made here, and the dairy plant is the biggest employer in town.