Determining the optimal light intensity is essential for the growth of Chlorella vulgaris and the production of suitable biomass for biodiesel. This study aims to investigate the cultivation of Chlorella vulgaris under optimal light intensity to enhance biodiesel production while ad-vancing the biological treatment of poultry slaughterhouse wastewater. To fill the relevant gap in the literature, the suitability of the biologically treated wastewater for microalgae growth was investigated at 20, 60, 100, and 140 µmolphoton/m2s light intensities with alkaline pH adjustment and pH shocking methods. Optimal phosphate and ammonium removal (up to 100%) was achieved using the alkaline pH method at 100 and 140 µmolphoton/m2s. In terms of biodiesel production, the most suitable result was obtained with the pH shocking method and the lipid ratio was calculated as 20% in the dry biomass of the C5.2 samples at 100 µ mol-photon/m2s.The highest chlorophyll-a concentration (3.32 mg/L) was measured in the same sample at 140 µmol photons/m²s. Fatty acid methyl ester species obtained predominantly C16 and C18 fatty acids at all light intensities. According to the results, Chlorella vulgaris grown at 100 µmolphoton/m²s is optimal for biodiesel production due to its high lipid content and fatty acid methyl ester types. Kinetic analyses showed that phosphate and ammonium removal predictability with Chlorella vulgaris followed first-order kinetics with R2 values of 96% and 85%, respectively. Under optimal light intensity, integrating Chlorella vulgaris cultivation into a biological slaughterhouse wastewater treatment system enables advanced treatment with re-al-world applicability.