Fluid loss control is crucial for efficient and safe drilling operations. Biopolymers offer a sustainable solution by minimizing fluid leakages and ensuring consistent performance. This study investigates the effectiveness of the carboxymethyl chitosan (CMC) biopolymer in controlling fluid loss in aerated drilling fluids under different laboratory conditions. The effect of polymer and surfactant (sodium dodecyl sulfate (SDS)) concentrations on rheological properties, fluid loss, stability, and bubble size was evaluated. Three drilling fluid samples were prepared with CMC concentrations of 1, 1.5, and 2 wt% to investigate the effect of concentration on rheological properties at 30°C, 50°C, and 70°C. The obtained results revealed that increasing the CMC concentration to 2 wt% increased plastic viscosity, apparent viscosity, yield point, and gel strengths. However, higher temperatures reduced viscosity due to increased kinetic energy and free movement of polymer chains. At a concentration of 2 wt%, the polymer formed a stronger gel network and reduced fluid loss to 20 ml while maintaining fluid properties. However, lower concentrations resulted in a weaker gel structure and higher fluid loss. Overall, increasing CMC concentration improved fluid rheological properties and reduced filtration rate, which contributed to better drilling fluid performance. In addition, the average bubble size decreased significantly with increasing CMC concentration, leading to greater stability because of higher viscosity of the drilling fluid at higher CMC concentrations. Furthermore, compared to molasses, CMC at a concentration of 2 wt% showed enhanced fluid properties, reduced fluid loss, and increased bubble half-life.