Heavy metals (HMs) contamination in the Eastern Harbor (EH), Alexandria, Egypt, presents serious environmental and health concerns. Increased industrial activities and urban runoff have raised pollutant levels in the area, impacting marine ecosystems and water quality. This study investigated the potential of biochar (BC) derived from marine macroalgae for removing (HM) ions from contaminated aqueous solutions. Biochar was produced through pyrolysis at 500°C, and its adsorption capacity was evaluated for the removal of Pb, Cu, Ni, Zn, and Cd. The physicochemical analysis revealed that marine macroalgae-derived biochar demonstrated exceptional removal efficiencies, ranging from 97 to 99% for the targeted (HMs). Among the macroalgae species assessed, Corallina officinalis was the most efficient bioaccumulator of Pb, Ni, and Cd, while Ulva compressa and Ulva fasciata showed the highest bioaccumulation of Fe, Cu, and Mn. These results highlighted the significant potential of algal biochar as a sustainable and effective material for the removal of HMs from contaminated water, offering an eco-friendly solution for pollution control and contributing to the development of circular economy practices.