Microalgae belong to the oldest forms of life, are found all over our planet and can be used commercially to produce specific food, feed and bio-chemical compounds. There are many microalgae strains that differ fundamentally in cell size, cell wall formation and biomass composition. In this chapter, the methods of microalgae cultivation and processing of microalgae-based biomass are described and compared. The cultivation process is performed in various open or closed bioreactor systems in salt, brackish or freshwater medium under different limited controlled conditions. Special processing requirements apply to the extraction of valuable compounds from microalgae biomass and further use of the residual biomass, especially in cascade utilization. By applying successive extraction procedures, both the principal fractions like proteins and lipids as well as high-value components such as pigments can be obtained sequentially from the microalgae biomass. In general, the chemical characteristics and market specifications, for example, the required degree of product purity, determine the downstream processing technique. In the last of the three sub-sections, a link is made to the biorefinery concept. The integration of microalgae cultivation into a biorefinery concept requires the closing of nutrient cycles, the utilization of residual flows such as nutrient-rich wastewater and industrial waste heat, and the ensuring of mild extraction processes that both maintain the functionality of the biochemical compounds and enable the extraction of further cell components.