This study presents the green synthesis of copper oxide nanoparticles (CuO-NPs) utilizing an extract from Carpobrotus edulis leaves, and evaluates their effectiveness in the removal of phosphate ions (PO₄^3-) and Malachite Green (MG) dye from aqueous solutions. The CuO nanoparticles (CuO-NPs) were subjected to physicochemical characterization, which indicated that the redox processes were carried out effectively. Furthermore, the material exhibited promising properties as a result of the removal of both types of pollutants such as numerous adsorption groups (carbonyl groups, phenolics, and other reducing agents), high specific surface area (301.2 m²/g), and pores of various sizes as shown by SEM and TEM. The percentage of elimination as a result of the best combination of variables in the adsorption process was obtained using a two-step optimization, namely the Taguchi experimental design (TED) followed by the response surface methodology (RSM). These findings indicate that the two-step optimization approach, incorporating both TED and RSM, achieves superior removal performance compared to the single-step process. The kinetic values were consistent with the pseudo-second-order model with higher R² and lower χ² and APE values. The maximum adsorption capacity of PO₄^3- and MG was determined by the equilibrium study, with 807.76 and 668.07 mg/g at 298 K, respectively, and the experimental values were most consistent with the Freundlich model. The exothermic and spontaneous nature of the adsorption process was confirmed by the thermodynamic values. Isothermal, pH_Z, and FT-IR results were used to explain the adsorption mechanism. The CuO-NPs exhibited effective adsorption capabilities in wastewater samples, along with notable reusability. After five regeneration cycles, the regeneration efficiency remained at 75.44% for PO₄^3- and 63.98% for MG, indicating sustained performance. These results underscore the viability of synthesizing CuO-NP using C.edulis extract and demonstrate their potential for applications in phytotoxicity assessment, antioxidant activity, and environmentally sustainable treatment of municipal wastewater.