[7] The mountain, and range, is named after Saint Brendan, and is the end of a Christian pilgrimage trail known as Cosán na Naomh.

[6] Mount Brandon owes its craggy shape to the work of glaciers during the ice age, which gouged out a series of corries on the eastern flank of the mountain.

[16] In the story of Brendan's life (titled, the Beatha Bhréanainn, or the Latin version, the Vita Brendani), he spent three days fasting on the mountain before his voyage, was visited by an angel, and experienced a vision of "a great land to the west";[17][18] the mountain is described as being surrounded by the ocean, which fits with the topography of Mount Brandon.

[4] Its importance may be due to the fact that, being so far west and so high, it is the place where the sun can be seen the latest as it sinks below the horizon.

[4] Tempan notes that the medieval story about Brendan's life calls the mountain Sliabh nDaidche in the Irish version, or Mons Aitche in the Latin version; and that the Irish academic Dr Alan Mac an Bhaird, had translated this as "mountain of Faithche", as Brandon stands in the Faha townland.

[22][23] A longer 5-hour variation is to continue north along the summit ridge from Mount Brandon to Piaras Mor, and then descend to Ballyknockane.

The route to the summit is marked, and offers views of the deep corries and paternoster lakes on Brandon's glaciated east face.

[4] The mountain's relative height and status of being at an extreme westerly point appears to have been of great importance to Saint Brendan.

[17][4] A pilgrimage route called Cosán na Naomh ("The Saints Road") begins at Cill Mhic an Domhnaigh (Kilvickadowning) on Ventry Strand at the southern end of the Dingle peninsula, and ends at Séipéilín Bréanainn ("Brendan's Oratory") on Brandon's summit.

[42] One of the routes chosen was Cosán na Naomh, and an 18–kilometre way-marked trail was constructed between Ventry Strand and the grotto at Ballybrack at the foot of Mount Brandon.

[44] For safety reasons, it was decided not to mark the trail to the end of the medieval route at the summit of Brandon, but to finish at Ballybrack.