What makes Moyne unusual is not simply its state of preservation, though it ranks among the best-preserved mendicant friaries in Ireland, but the accumulated detail that survives within it: patches of wall plaster in the nave bearing unique etchings of boats, scratched there by unknown hands sometime in the sixteenth or seventeenth century; an entire cloister of integrated type, where the upper floor of the domestic ranges extends over the barrel-vaulted ambulatory below; and beneath those same ranges, a stream that the friars built directly over, using it to supply water and carry away waste. The mill whose remains still stand to the east of the complex fed off the same watercourse.

The friary was founded around 1455 as an Observant house, part of a reform movement within the Franciscans that emphasised a stricter return to the founding rule of poverty. The austerity of the architecture reflects this: there is almost no decorative carving, and what ornament exists, the switchline tracery in the chapel windows, the quatrefoils set into the window heads, the moulded capitals on the octagonal nave pillars, is restrained by the standards of the period. The church was consecrated in 1462 by Donatus O'Connor, Bishop of Killala, and the friary was almost certainly established under the patronage of the Mac William Burkes, lords of Lower Connacht. Provincial chapters of the Irish Franciscan Observants met here six times between 1464 and 1550. The piecemeal character of the building, the lateral aisle and southern chapel built in a slightly different masonry fabric to the nave, indicating they came slightly later, reflects a common pattern in Irish mendicant construction, where elements planned from the outset could only be built as donations came in. After the Dissolution, the Mac William Burkes shielded the friars for a time, but the friary was attacked in 1579 and again in 1582. In 1590, Sir Richard Bingham, governor of Connacht, burned it. The property passed to an Edward Barrett in 1595, and by 1616 just six friars remained, renting space from an English widow who had taken over the building.

The complex is a National Monument in state care, and the completeness of its fabric rewards a slow visit. The integrated cloister, where the upper dormitory floor projects out over the walking arcade, is particularly rare in its intact condition. A possible hospital lies roughly seventy metres to the east of the main precinct, and an eighteenth-century house was later attached to the eastern domestic range, a reminder that the site continued to be inhabited and adapted long after the friars were gone. Rosserk Franciscan friary, similarly well-preserved and architecturally close in character, stands about five kilometres to the south-east on the banks of the River Moy.