Kyllinga beninensis Samain, Reynders & Goetghebeur, a new species of Cyperaceae from the Borgou-Sud region of Bénin, is fully described and illustrated. This species can be recognized by the slender habit with swollen stem base, the tiny white head consisting of a single spike, and the spikelets with two glumes and one flower. Morphological differences with the species K. microbulbosa Lye from East Africa, to which K. beninensis bears a superficial resemblance, are discussed.