Photoluminescent composites that are air-stable and water-resistant are important for outdoor applications such as road marking paints, light-converting membranes, fluorescent paints, and security inks. Photoluminescent thermoplastics fulfill all conditions but their preparation methods which are vastly based on mixing pre-synthesized fluorescent dyes and plastic could lead to emission quenching due to dye aggregation or thermal degradation. Herein, we demonstrated a simple method to prepare photoluminescent polycarbonate by thermal extrusion polycarbonate with citric acid and urea. UV-vis absorption and photoluminescent studies indicate that fluorescent carbon materials were formed via pyrolysis of the citrate. The composites exhibit light blue emission and a broad excitation band. The results demonstrated herein offer a cost-effective method to prepare diverse photoluminescent composites for outdoor applications.