In this paper, we describe and illustrate Piper lanyuense K.N. Kung & Kun C. Chang sp. nova (Piperaceae) from Orchid Island, Taiwan. Piper lanyuense was previously misnamed P. philippinum or P. kwashoense. The new species closely resembles P. betle, a widely cultivated species in South and Southeast Asia, but can be distinguished from it by its erect inflorescence, red and globose drupe, and the lower number of stigmas. A key to the four species of the genus Piper from Orchid Island is provided.