The green synthesis of carbon dots (CDs) from renewable resources has attracted attention of the scientific community for their use in different...The green synthesis of carbon dots (CDs) from renewable resources has attracted attention of the scientific community for their use in different industrial applications. CDs derived from microbial biomass can be synthesized using simple and low-cost methods, and have been reported to possess high compatibility, excellent optical behavior and low toxicity. In this study, carbon dots were synthesized using lipids and carbohydrates extracted from microalga Acutodesmus obliquus via microwave hydrothermal digestion method. The synthesized carbon dots showed excitation peaks in the ultraviolet light region (c.a. 350 nm) and emission in the visible region (c.a. 420 nm). The addition of acetone led to red shifting of excitation wavelength in all the synthesized carbon dots. The transmission electron microscopy analysis depicts the nano-size (1.2–11 nm) range of the synthesized carbon dots, where excitation and emission wavelengths were not dependent on the size of the particles. Carbon dots prepared from microalgal metabolites showed fluorescence under ultraviolet luminescence in different wavelengths after the addition of chemicals. The carbon dots thus generated can be explored for their applications such as dyes, sensors, bioimaging and photosensitizers.