Rhododendron fallacinum is a species of rhododendron native to Borneo.
It a hemiepiphytic shrub or small tree which grows up to six meters tall.
It is native to the mountains of Sabah and Sarawak states of Malaysia in northern Borneo, including Mount Kinabalu, Mount Trus Madi, and the Crocker Range in Sabah and Mount Mulu in Sarawak. The species' estimated extent of occurrence (EOO) is 17,011 km2, and its area of occupancy (AOO) is 120 km2.
It lives in montane forests from 1,200 to 2,600 metres elevation. It grows mostly as a terrestrial shrub, and less commonly as an epiphyte, in damp shady areas of mossy montane rain forest. It also grows among other shrubs on open ridges and rocky slopes, where it can be the dominant species.