This research examined the seasonal fluctuations in the nutrient remediation capability of the jointed flatsedge in eutrophic waterbodies through biomass harvesting and estimation of its potential use as animal feed. Samples of plants, water, and sediment were gathered seasonally from six polluted and three unpolluted sites. Fall had the highest biomass (3341.6 g/m2) and summer had the lowest (283.8 g/m2) in polluted waterbody with an average of 1.17 kg/m2 lower than in the unpolluted Nile (1.39 kg/m2). The aboveground parts had their highest contents of K, N, and Ca (174.4, 11.3, and 12.4 mg/kg, respectively) during fall, and Na, P, and Mg during spring, while belowground parts had their highest Na content (165.9 mg/kg) in winter, and Ca and P (13.3 and 5.4 mg/kg) in spring. Summer contributed to the highest contents of crude fibers and protein contents (58.4 and 9.8%) in aboveground shoots, while spring had their highest value (31.1 and 7.3%) in the belowground organs. Moreover, fall months had the highest efficiency in removing Na, K, N, Ca, and P (0.94, 0.59, 34.75, 37.77, and 17.77 g/m2) by shoot tissues. Therefore, jointed flatsedge has the efficiency to remediate nutrients from eutrophic waterbodies by harvesting aboveground biomass, especially in the fall.