The R747 originally ran from a junction with what was then the N9 in the the townland of Timolin, 2.3 km east of its present starting-point. This junction was shifted eastwards by a further 100 m in 2001 when improvements to the N9 through Timolin saw the National road realigned.
With the opening in December 2009, on a course running further to the west, of a new high-quality dual-carriageway (HQDC) section of the N9 (declared upon completion to be of motorway standard and therefore given the designation M9), the "old N9" was reclassified as the R448.
At the same time, and in conjunction with these developments, a new link road, the N78, was built from Athy to connect to Junction 3 of the motorway – and this new link (designated R747 east of the motorway) was extended to meet the R448 at Timolin, thus giving our road its present length.