Cold-adapted microalgae display unexpectedly high biomass production, pointing to their potential to produce high-value bioproducts under cold and light-limited conditions. From culture collections, we screened eight cold-adapted strains of different genera (Chlamydomonas, Chlorella, Tetraselmis, Pseudopleurochloris, Nannochloropsis and Phaeodactylum) for the production of fatty acids and proteins under low temperature and light regimes (T = 8, 15 °C; I = 50, 100 μmol s−1 m−2). Among the strains, the Arctic isolate Chlamydomonas sp. (RCC 2488) had better growth at 8 °C compared to 15 °C (up to 0.5 gDW L−1 d−1) and highest productivities of protein and polyunsaturated fatty acids (PUFA) (70 and 65 mg L−1 d−1, respectively). Two tested Tetraselmis strains (SAG 1.96, RCC 2604) achieved highest biomass productivities (0.7–1 gDW L−1 d−1), containing up to 50 mg PUFA gDW−1 and 15% proteins. Pseudopleurochloris antarctica (SAG 39.98) grew well at 15 °C (0.4 g L−1 d−1), with 23% proteins in biomass and the highest eicosapentaenoic acid (EPA) productivity (7.6 mg L−1 d−1). Chlorella stigmatophora (RCC 661) achieved productivities of 0.4 gDW L−1 d−1 at 15 °C and produced extracellular polymeric substances (EPS). The major cause for the observed shifts in biochemical profiles was biomass concentration, which is an indicator for the prevailing growth stage. Based on the current experimental design, Chlamydomonas sp. (RCC 2488), T. chuii and P. antarctica can be suggested as the most promising strains for the production of protein and (polyunsaturated-) fatty acids at low temperatures. However, additional strain-specific studies are necessary to statistically validate these findings.