Fáelán is believed to have first entered the monastic life at Taghmon (Co. Wexford), which was established by Fintan (qv) (d. 637) in the seventh century. He later entered a monastery at Pittenweem in Fife, eventually becoming abbot. He retired to Glendochart in Perthshire, where placenames and dedications still recall his memory, and was buried at the church of Strathfillan. A staff claimed to have been his is preserved in the National Museum of Scotland. He is recorded in the Irish and Scottish martyrologies. The Martyrology of Óengus (qv) (fl. c.830) and the Martyrology of Gorman (Máel Muire Ua Gormáin (qv)) describe him as Fáelán of Ráth hÉrenn; the Martyrology of Óengus also refers to him as ‘Fáelán with that victory, that splendid mute’.
The veneration of Fáelán was such that Robert the Bruce is said to have taken the relic of his arm into the battle of Bannockburn (1314), and attributed his victory to it. The feast-day of St Fáelán is variously celebrated on 9 January and 20 June; while many saints have two feast-days, it is possible that Fáelán was later confused with an earlier person of the same name – possibly the Fáelán whose name survives at Kilwhelan, Co. Laois.