The provision of adequate and sufficient nutrition is of paramount importance, especially in developing nations. Thus to ensure the provision of proper and adequate nutrition to such populations, exploitation of underutilized food varieties is crucial; however, Cyperus esculentus is widely consumed in Nigeria but its close relative Cyperus rotundus is sparingly eaten. The phytochemical and nutritional compositions of two Cyperus species, namely, C. rotundus (nutsedge) and C. esculentus (tiger nut) of Cyperaceae were evaluated using high-performance liquid chromatography. The phytochemical analysis reveals total alkaloids, flavonoids, phenolics, and glycoside concentrations (g/100 g) of 14.14, 35.55, 29.23, and 14.74, respectively, in tiger nut while that of nutsedge is 16.44, 38.68, 23.23, and 13.26, respectively. Tiger nut vitamin composition includes Vit. B1 3.00%, Vit. B2 0.72%, Vit. B3 0.042%, Vit. B6 0.93%, Vit. B12 4.00%, Vit. C 0.07%, and Vit. E 0.05% while that of nut sedge includes Vit. B1 1.00%, Vit. B2 0.0.97%, Vit. B3 0.05%, Vit. B6 1.00%, Vit. B12 3.00%, Vit. C 0.10%, and Vit. E 0.03%. The concentration of these vitamins (Vit.) in both species was relatively low compared to Vit. A with 19.02% in tiger nut and 15.02% in nutsedge. Other phytochemicals detected include saponins (5.00 ppm for tiger nut and 7.00 ppm for nutsedge), tannins (6.00 ppm for tiger nut and 8.00 ppm for nutsedge), oxalate (4.01 ppm for tiger nut and 3.01 ppm for nut edge), and phytates (6.04 ppm for tiger nut and 7.05 ppm for nutsedge). The presence of these phytochemicals confirms the medicinal abilities of these two Cyperus species.