Macroalgae (or seaweeds), are multicellular, photosynthetic algae growing predominantly in marine environment by attaching to suitable substrate. Biomass are composed of structural and storage carbohydrates that have varied multi-functional properties and are exploited in the form of food, medicines, cosmetics and energy. Sustainable utilization of macroalgal biomass for biofuel production has attracted a lot of attention in recent times and has been emerging as potential sustainable alternative to the conventional gasoline-based fuel. This chapter introduces macroalgal structure, habitat, physiology, biochemical composition followed by the global distribution of macroalgal resources and the state-of-the-art technology involved in the conversion of macroalgal biomass for production of biofuel and the constraints encountered in these conversion technologies as well as opportunities to establish a macroalgae based biorefinery. Concluding section discusses, availability of macroalgal resources along East and West coast of India and economic prospects of seaweed for biofuel production.