To enhance the mechanical, thermal, and electrical properties and economic profits, polycarbonates (PCs) have been blended with various inorganic additives for the past few decades. Herein, we fabricated basalt fiber (BF)-infiltrated PC composites as a promising candidate for a myriad of PC applications. Mechanical robustness and rheology were examined via the precise control of BF contents (up to 12.5 phr). The incorporation of BF gradually enhanced the mechanical properties of the composites such as moduli and strengths, as determined by flexural and tensile tests. The Izod impact strength was reduced as a function of BF concentration, representing the ductile-to-brittle transition. The heat deflection temperature of the PC/BF composites was increased from 131.2 degrees C to 138.9 degrees C, which was in good agreement with the thermomechanical results. By contrast, the glass transition temperature measured by differential scanning calorimetry remained unchanged at ca. 143 degrees C. The incorporation of BF in PCs enhanced the dimensional stability. The visual observation for PC/BF composites was examined via scanning electron microscopy. The rheological investigation was systematically performed by utilizing the melt flow index, and capillary and torsional rheometry with a variety of experimental conditions. These PC/BF hybrid composites with tunable mechanical and rheological properties will be employed for various applications by tailoring the PC/BF ratios. (C) 2018 Elsevier Ltd. All rights reserved.