Microalgae have emerged as potential candidates for the remediation of heavy metal-contaminated wastewater owing to their metal uptake capacity and metabolic adaptability. In this study, the potential of Monoraphidium sp. (NCIM-5792) for hexavalent chromium [Cr(VI)] remediation was evaluated under photoautotrophic conditions at initial Cr(VI) concentrations ranging from 1 to 30 mg/L. NCIM-5792 achieved a maximum Cr(VI) removal efficiency of 99.4% at 1 mg/L, which gradually decreased to 54.8% at 30 mg/L. Chromium exposure adversely affected cellular growth, resulting in a reduction of biomass from 0.46 g/L in the control to 0.17 g/L at 30 mg/L Cr(VI). Similarly, protein and carbohydrate contents declined progressively with increasing Cr(VI) concentration, indicating substantial metabolic disruption under chromium stress. In contrast, lipid accumulation increased significantly at 10 mg/L of Cr(VI) exposure, as confirmed by gravimetric lipid estimation, Nile Red fluorescence, and FTIR analysis, suggesting a stress-induced metabolic shift toward lipid biosynthesis. Comparative analysis of Cr(VI) and total chromium concentrations further suggested the formation of chromium species in its reduced form, likely to be Cr(III) during treatment. Collectively, the results demonstrate that Monoraphidium sp. (NCIM-5792) combines effective Cr(VI) remediation with distinct metabolic adaptations under chromium stress. To the best of our knowledge, this is the first comprehensive study reporting the Cr(VI) remediation potential, physiological responses, and stress-induced lipid accumulation of Monoraphidium sp. (NCIM-5792), highlighting its potential for sustainable chromium bioremediation and wastewater treatment applications.