Wastewater and carbon dioxide (CO2) pollution are the most serious issues all over the world. Microalgae have been identified as one of the best possible solutions for the above mentioned problems. Microalgae are microscopic photosynthetic organisms, which help to uptake the organic nutrients present in the wastewater along with the CO2 present in the atmosphere to produce biomass with high contents of carbohydrates, proteins, lipids, vitamins, minerals, etc. All these molecules can be utilized for the production of different commercial products when microalgae are grown on a large scale. Wastewater from municipal, industrial, agro-industrial, and livestock can be used to grow microalgae which helps to reduce or absorb the total organic carbon (TOC), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), ammonia nitrogen (NH4-N), and heavy metals resulting in water for reuse. CO2 present in the atmosphere is utilized by the microalgae with higher efficiency than plants and hence the mitigation of CO2 can be made better. The obtained biomass can be used to produce different forms of bioenergy like biodiesel, bioethanol, biohydrogen, biomethane, bioelectricity, and biochar. Hence, sequestration of pollutant by microalgae along with biomass production provides much support to cost-effective biofuel production. In this chapter, an overview of recent updates about microalgae-based technologies emphasizing sustainable biofuel production is given.