Life cycle assessment (LCA) of microalgae-based systems for wastewater treatment and resource recovery examines the potential of microalgae-based systems for treating wastewater and extracting resources. Microalgae, photosynthetic microorganisms found in diverse aquatic environments, offer significant ecological and technological benefits. Their metabolisms are such that they can remove nutrients and contaminants from wastewater thus providing a sustainable and less expensive alternative to conventional treatment methods. Through this assimilation process, nitrogen and phosphorus levels can be controlled thereby reducing eutrophication, while heavy metal levels are reduced lowering the discharge of hazardous substances into the rivers, lakes, or seas. Life cycle assessment (LCA) methodologies are employed to evaluate the environmental sustainability of these systems, revealing trade-offs and opportunities for improvement across different stages of the product life cycle. This chapter addresses the biological characteristics, traditional uses, as well as modern day applications of microalgae with an emphasis on its significance to environmental sustainability. It explores recent developments in technology, integrated system approaches, practical applications, and offers guidance for future urbanization based on these trends.