Aluminium matrix composites (AMCs) have attracted significant attention because of their high specific strength, low density, and excellent corrosion resistance. This study aimed to fabricate AA6061 hybrid aluminium matrix composites reinforced with SiC (5-15 wt.%), TiC (4-8 wt.%), and marble-processing waste in the form of marble dust (2-6 wt.%) using the stir casting process and to optimize their mechanical performance through statistical techniques. A Taguchi L9 array was employed for experimental design, while density, porosity, tensile strength, and impact strength were experimentally evaluated. Microstructural characteristics were examined using scanning electron microscopy before and after mechanical testing. Experiment 6 exhibited the highest tensile strength of 179.14 MPa and a porosity of 1.0814%, and highest Grey Relational Grade 0.755296, whereas the maximum impact strength of 268.25 kJ/m2 was obtained for Experiment 1. Taguchi-Grey Relational Analysis (GRA) predicted 10 wt.% SiC, 4 wt.% TiC, and 2 wt.% marble dust as an optimum reinforcement combination, indicating that statistically optimal parameter combination differed from best performing experiment included in L9 design. Analysis of variance identified SiC as the factor with the highest relative contribution to GRG variation, followed by marble dust and TiC. The confirmation experiment at the predicted optimum condition produced a Grey Relational Grade of 0.7085, which was 18.76% higher than the overall mean GRG. The results demonstrate that the combined incorporation of ceramic reinforcements and marble-processing waste, together with Taguchi-GRA, provides an effective approach for optimizing the multi-response performance of AA6061 hybrid composites while enabling value-added utilization of marble-processing waste in Al alloys.