Existing water resources cannot satisfy human needs due to an increase in population, the growth of urbanization, and the scarcity of freshwater sources worldwide. Utilizing plant species, microbes, algae, or a mix of these can be used to effectively desalinate seawater through biological processes. The objective of this study was to investigate the possibility of seawater desalination by using green microalgae (Chlorella vulgaris, Scenedesmus quadricauda, and Dunaliella salina) and the potential for combining it with the manufacture of biodiesel. The results showed that Chlorella vulgaris and Scenedesmus quadricauda were significant for the desalination of seawater. The TDS removal percent reached 82% and 79% during the culturing of Chlorella vulgaris and Scenedesmus quadricauda (respectively), without adding any nutrients while the removal percent reached 82% and 80% (respectively), during culturing with adding nutrients. The results of Dunaliella salina showed that there is no significant difference in the desalination of seawater. Characterization of the algal biodiesel obtained from Chlorella vulgaris and Scenedesmus quadricauda revealed that it fits the international specifications.