This chapter discusses the cultivation of microalgae under heterotrophic and mixotrophic conditions in terms of market pull (societal challenge and demand readiness level) and technology push (technology readiness level). Heterotrophic cultivation, possible on microalgae strains presenting the needed metabolic pathways, benefits from the already developed microbial biosynthesis technological subsystems—bioreactors/fermenters, downstream processing equipment, (bio)sensors, and automated control. Large-scale production of high value-added ingredients (e.g., phycobilins or carotenoids like astaxanthin) is technologically possible and responds to an increasing demand for bioactives. Mixotrophic cultivation has the advantages of reduced operation cost and higher yield. Such a cultivation technique, which enables transformation of waste with solar power into algae mass, is therefore a key enabling technology for a circular bioeconomy. Mixotrophically grown microalgae sequestrate CO2 while simultaneously synthesizing value-added products. In summary, this chapter reviews the present evolution of heterotrophic and mixotrophic cultivation technologies of microalgae and identifies several research and innovation needs for better harnessing the microalgae's potential.