Microalgae-based wastewater treatment offers a sustainable alternative to conventional physical and chemical methods, with advantages such as effective nutrient removal, CO2 sequestration, and the potential to produce valuable biomass. However, traditional suspended cultivation of microalgae faces several challenges, including low nutrient recovery, high biomass harvesting costs, and the non-reusability of biomass, which limit its application for large-scale wastewater treatment. To overcome these limitations, a novel approach, immobilized cultivation of microalgae coupled with wastewater treatment, gained significant attention in recent years. In this method, microalgal cells remain attached to or entrapped within a solid support matrix, which facilitates harvesting easier, improved biomass reusability, and enhances operational stability. In this context, the present chapter highlights recent advancements in microalgal immobilization techniques, including both passive and active methods. It also outlines the mechanisms of biofilm formation, explores various types of microalgae immobilization systems, and discusses key factors affecting growth and nutrient uptake, such as substrate properties, light, temperature, and pH. Furthermore, it compares the benefits and limitations of immobilized versus suspended systems. The information and perspectives provided in this chapter can serve as a valuable reference for upgrading microalgae-based nutrient recovery from wastewater.