<p>The increasing need for hybrid aluminium nanocomposites (HNCs) is motivated by their exceptional mechanical qualities that satisfy the rigorous demands of advanced engineering applications. This work involved the development of Al6061 matrix composites, strengthened with 4 wt% fly ash and different quantities of yttria (Y₂O₃) (1 wt%, 2 wt%, 3 wt%) using the stir-casting method. The composite material Al6061/4 wt% fly ash/3 wt% Y₂O₃ demonstrates superior properties compared to the unreinforced sample. This shows the ultimate tensile strength of 170.38 MPa and the yield strength of 115 MPa, which were 123.6% and 270.9% greater than those of the unreinforced base alloy, respectively. The observed value for the microhardness is 123.25 HV, which is 135.6% higher than that of the base alloy. However, the impact strength of 35 J for the unreinforced specimen decreased to 27.98 J for the composite with the highest hard ceramic yttria content, due to an increase in hardness and a decrease in ductility. The novelty of this study lies in the synergistic use of fly ash (a low-cost industrial by-product) and yttria (a high-performance ceramic) as hybrid reinforcements in Al6061, offering a sustainable and cost-effective route to developing high-strength aluminium nanocomposites. The present work focuses on correlating the uniform nanoparticle distribution and grain refinement achieved through stir casting with the exceptional improvements in the mechanical performance of Al6061 hybrid nanocomposites.</p>