The mechanical properties of components manufactured by fused filament fabrication lack sufficient levels for industrial applications. The need for post‐processing is, therefore, necessary to enhance the interlayer strength and mechanical characteristics. In the present study, experimental analysis of the effects of annealing on polycarbonate acrylonitrile butadiene styrene manufactured by fused filament fabrication is explored. Annealing temperatures are selected in the range from 90 to 210°C based on differential scanning calorimetry analysis. The ultimate tensile strength improved by 20.39% from 32.39 to 38.99 MPa after the heat treatment at 180°C for 1‐h duration. Flexural strength showed a remarkable enhancement of 53.21% after annealing at 180°C for 2 h. The interlayer diffusion and bonding are boosted following heat treatment and microstructural imaging proved the same although the surface had flakes due to the high heat exposure. X‐ray diffraction testing of annealed models demonstrated a maximum crystallinity index of 32.56% when compared with nonannealed samples with 6.58%. The addition of polycarbonate to acrylonitrile butadiene styrene improves the stiffness and impact loading capacity with high heat resistance. The heat treatment process is capable of magnifying the mechanical characteristics of the end functional components, thereby opening up the scope for more engineering applications.