Background – Hydnophytum puffii Y.W.Low, Sugau & K.M.Wong, a linear-leaved epiphytic ant-plant is described as new from Borneo using morphological characters based on specimens preserved in the Sandakan and Singapore Herbaria. This new species is so far known only from Sabah, Malaysia.Methods – This study is based on herbarium materials and field observations in Sabah. Conventional herbarium techniques were applied for taxonomy, while the IUCN conservation status was assessed using GeoCAT.Results – Hydnophytum puffii is closely related to H. angustifolium Merr. but differs in having glabrous young twigs, 4–5 pairs of leaf secondary veins on the lower leaf surface, a corolla tube that is densely covered with translucent hairs inside the throat around the anthers, and prolate mature fruits. This new taxon is the only species in Borneo to have linear leaves as the other two taxa, namely H. coriaceum Becc. and H. formicarum Jack have broad elliptic leaves.