Decaisnina samaense, a new species of Loranthaceae from the Island of Simunul, Southern Philippines, is hereby described and illustrated. It is distinguished from all Decaisnina species by having narrowly lanceolate and narrowly ovate-lanceolate leaf laminae with a remarkable acuminate apex, flower buds being globularly inflated at the base with corolla color being yellow in the lower half and pastel green in the upper half and often blackish at the tip, and inflorescence consistently produce both triads and peduncles along the axis. It is related to Decaisnina stenopetala and D. zollingeri by exhibiting globular inflation at the base of the flower buds but differs from the two by having longer bracts, longer anthers, and the free part of the filament shorter. Decaisnina samaense is hereby assessed as Critically Endangered (CR B1, B2a&c, D).