Kilflynn or Cill Flainn as it would originally have been called, means the church or oratory of Flainn. This may be linked with the O'Flannan tribe who, along with the tuath Ui dTorna, gave their name to the rural deanery of Othorna and Offlannan in the 12th and 13th century. But the more commonly held believe is that the village is called after St. Flainn, the hermit monk.
Kilflynn is situated in the barony of Clanmaurice which runs from the mouth of the river Feale in the west to Barrow Harbour and on to the Limerick border three miles west of Abbeyfeale. In a north south direction it runs from the Feale to the Stack and Glanruddy Mountains . The village itself is built on the southern bank of the river Shannow.
The barony takes its name from Fitz Maurice family, a branch of the Geraldines from Florence in Italy , who came to Ireland in 1172. They were later honoured with the title of Lord Kerry. The great centre of their power was the ecclesiastical city of Ardfert , but their castle strongholds lay along the line of the Feale from Listowel to Ballybunion. The high ground above Kilflynn village was an ideal home for the Fitzmaurice castle of Garrinae . This strategic position gave a splendid view of the coast from Tralee Bay to Kerry Head and the mouth of the Shannon .
After building the Court at Lixnaw the Fitzmaurices left Castletown to their Norman
in-laws, the Stacks. This is the same Stack family who made their residence at Crotta and lent their name to Kilflynn in the middle ages when it was known as Stackstown.
The barony, like the townland of Kilflynn has been spelt in many different ways over the years. The 17th century map from the William Petty survey shows KIFONIE in the barony of CLANMORRIS.
In 1837 Lewis described the parish of Kilflynn as "comprising 6481 statute acres, as aplotted under the tithe act, of which upwards of one half consists of coarse mountain pasture; the remainder with the exception of about 270 acres of bog, is good arable land".
Kilflynn was once a large village on the main road to Limerick . But the passing traffic was diverted by the advent of what is now the main Tralee-Listowel road, known as the New Line, in 1846, and then the railway line a year later bringing the passing trade via Lixnaw the village fell into decline. The population shrunk from 738 in 1881 to 669 in 1891. By 1901 there were 584 people living in the Kilflynn electoral district. According to the most recent census (1991) this figure has fallen yet again, to 295.