Arthrospira platensis and Chlorella vulgaris are popular commercialised microalgae due to their benefits and relatively easy large-scale cultivation. However, recent advances in biotechnology have revealed a new range of promising strains with industrial potential but limited current markets. To bridge the gap in the existing literature, this study provides a comprehensive and simultaneous biochemical characterisation within a unified analytical framework of six additional strains: Phaeodactylum tricornutum, Tetraselmis chuii, Nannochloropsis oceanica, Scenedesmus almeriensis, Tisochrysis lutea, and Skeletonema costatum. The analyses included macromolecular composition, amino acid and fatty acid profiles, and volatile organic compound composition. Key results identified P. tricornutum and T. chuii as high-quality protein alternatives, reaching protein concentrations of 31% and 41% (dw), respectively, with essential amino acid profiles (arginine and tryptophan) that match commercial standards. Additionally, specific carbohydrate and lipid strengths were identified: P. tricornutum showed a high carbohydrate content (37%), while N. oceanica exhibited elevated levels of palmitic, palmitoleic, eicosapentaenoic, and arachidonic acids, marking them as versatile candidates for nutritional applications. Finally, volatile organic compound analyses revealed distinct aroma profiles, highlighting the potential of less-exploited microalgal strains for the food and feed sectors.