In this study, activated carbon has been obtained by using sea urchin as an adsorbent substance, which is abundant, cheap, and natural in nature, as an alternative to active carbon used in heavy metal removal. Using the Ultrasound-assisted support, 1:1, 2:1, 3:1 (H3PO4/sea urchin) carbonization process was carried out by subjecting H3PO4 as the sea urchin activating agent. The BET surface area of the activated carbon obtained was characterized by total pore volume, ash content, and SEM analysis. Cu (II) removal in aqueous solutions were investigated with activated carbons. Experimental studies have been conducted to determine the effects of pH, contact time (min), adsorbent concentration (g/L), temperature, and initial metal concentration parameters affecting adsorption. The adsorption capacity of the activated carbon obtained from the sea urchin at 25 °C was calculated as 643 mg/g. Optimum conditions from the results were determined as pH 2.0, contact time 80 minutes, initial adsorbent concentration 10 mg/L, and temperature 25 °C. According to the results of the study, it has been concluded that the activated carbon obtained from the sea urchin can be an alternative adsorbent to other activated carbons in heavy metal removal.