The species is named for the type locality Bukit Lawang.
This species was named in the following publication:
Mat Salleh K, Mahyuni R, Susatya A, Veldkamp JF. 2011. Rafflesia lawangensis (Rafflesiaceae), a new species from Bukit Lawang, Gunung Leuser National Park, North Sumatra, Indonesia. Reinwardtia 13: 159-165.This species is known only from Bukit Lawang, Gunung Leuser National Park in North Sumatra. Although previously thought to be either R. arnoldi var. arnoldii or R. arnoldii var. atjehensis, this species differs from that species in a number of characters. It resembles R. kerrii from peninsular Thailand and Malaysia in possessing a very wide diaphragm opening, but differs from that species in lacking windows in the diaphragm. It differs from R. arnoldii by the presence of pubescence on the upper surface of the perigone lobes, smaller flowers, and wart shape and color. The range of this species overlaps two others, R. micropylora and R. rochusenii but is easily differentiated from them, as well as Sumatran species with non-overlapping distributions such as R. bengkuluensis, R. gadutensis, and R. hasseltii.