The algal biorefinery remains a highly promising and dynamic field, offering a sustainable pathway for producing a diverse range of high-value products from microalgae. As a renewable biomass resource, algae can be refined into lipids, proteins, peptides, carotenoids, pigments, and carbohydrates, making it a versatile feedstock for industrial applications. This approach aligns with global sustainability goals, positioning algal biorefining as a key driver in the transition toward biomass-based industries. A critical aspect of algal biorefinery is the upstream process, which includes cultivation and harvesting two stages that significantly influence productivity and economic viability. Recent advancements in cultivation techniques, such as optimized photobioreactors, open pond systems, and nutrient stress strategies, have enhanced biomass yield. Similarly, innovations in harvesting methods, including flocculation, centrifugation, and membrane filtration, aim to improve efficiency while reducing costs. However, challenges such as scalability, energy consumption, and contamination risks persist, requiring further research and technological refinement. This chapter explores these upstream processes in detail, highlighting the latest developments, ongoing challenges, and future prospects in microalgae cultivation and harvesting for sustainable biorefinery applications.