In situ coverage is a commonly used method for the remediation of eutrophic sediments. Carbon-based materials offer several advantages, including widespread availability, environmental friendliness, and the absence of secondary pollution, particularly when compared to other remediation options. In this study, we pre-treated and structurally characterized activated coke and assessed its potential for sediment remediation for the first time. We examined the effects of activated coke (363.9 g/m2) and the submerged aquatic plant (Hydrilla verticillata, 32.4 g/m2) both individually and in combination on nutrient release from eutrophic sediments, as well as the impact of activated coke on the growth of submerged plants. The results demonstrated that activated coke possesses a high specific surface area and a rich mesoporous structure. Compared to the control group, the concentrations of CODMn, Chl.a, TN, TP, NH3-N, and SRP in the overlying water, as well as the total release fluxes of TN, TP, NH3-N, and SRP from the sediments, were significantly reduced. The combination treatment of activated coke and submerged plants yielded better results for the overlying water and sediment indicators than either treatment alone. Furthermore, the activated coke treatment increased the growth rate of submerged plants by 40.32% and significantly reduced the amount of reactive phosphorus within the plants, thereby decreasing the risk of phosphorus release after their decay. These findings indicate that activated coke has strong potential for application in the ecological restoration of eutrophic water bodies and exhibits a synergistic effect when combined with submerged plants.