Seaweeds have been used in many biotechnological applications ‎including animal feed, human food, cosmetics, fertilizers, and ‎bioremediation. With respect to bioremediation, seaweeds contaminated ‎with heavy metals have limited applications and most suited for biofuel ‎production. The present study aimed to evaluate the potential of ‎seaweeds for dual use in heavy metal biosorption and biofuel production. ‎Three dominant seaweed genera were collected representing the three ‎macroalgal phyla, namely Ulva spp. (Chlorophyte), Gracilaria spp. ‎‎(Rhodophyte), and Sargassum spp. (Phaeophyte). The later showed the ‎highest cumulative copper (Cu2+) biosorption with 80% removal ‎efficiency, which increased to 94.6% after process optimization. ‎Comparative fermentation of raw biomass (RB) and Cu-sorbed biomass ‎‎(BHM) showed the highest bioethanol yield of 289.2 mg g L-1 for RB at ‎‎72 h fermentation, which was 24.3% higher than that of BHM. In ‎addition, the presence of Cu+2in the BHM showed significant reduction in ‎biogas and biomethane yields by 18.4% and 5.2%, respectively, with ‎respect to RB. However, fermented BHM showed higher biogas and ‎biomethane yields than the fermented RB. Due to dual bioethanol and ‎biogas production, sequential fermentation and anaerobic digestion of ‎Cu-sorbed biomass showed the highest energy output of 1597.3 GJ year ‎L -1. The present study suggests a novel approach that provides an ‎integrated method for efficient utilization of seaweeds biomass in ‎wastewater treatment and sustainable energy recovery.‎