Microalgae are emerging as a viable alternative feed source for various sectors, including livestock, aquaculture, poultry, and agriculture, due to their high nutritional components (carbohydrates, proteins, lipids, and vitamins), bioactive substances, and sustainability. This chapter provides a comprehensive overview of microalgae cultivation, processing techniques, the integration of algae in feed, various methods for feed formulation, the nutritional stability of algal feed, and its challenges. It describes the key parameters that affect microalgal growth, biomass quality, nutrient composition, and strategies to enhance the nutritional profile. Additionally, this chapter discusses different techniques for incorporating microalgal biomass into feed as a supplement, such as drying, pelleting, and encapsulation techniques, along with their advantages and limitations. It concludes by emphasizing the potential of microalgae to contribute to the sustainable development of global animal husbandry and aquaculture industries, paving the way for more eco-friendly and nutritionally balanced feed formulations.