Several biofuel candidates were proposed to displace fossil fuels in order to eliminate the vulnerability of energy sector. Biodiesel and bioethanol produced from terrestrial plants have attracted the attention of the world as potential substitute. However, due to food vs. fuel competition as well as land consumption of these biofuel, they have brought much controversy and debate on their sustainability. In this respect, cultivation of macroalgae such as seaweed at sea water which does not expend arable land and fertilizers provides a possible solution for this energy issue. Carbohydrates derived from seaweeds contain hexose sugars which are suitable materials for fermentation to produce ethanol. Therefore, it is possible to produce fuel ethanol from seaweeds. The potential and prospective of seaweeds to play the role as a sustainable energy provider are demonstrated in this paper. This study offers a conceivable picture of macroalgae-based third-generation bioethanol biorefinery to stimulate the initiation of the exploration in the related field.