Al-based TiC particle-reinforced composites with varying TiC concentrations were fabricated through semi-continuous casting. The effects of TiC particles on the alloys’ microstructure, grain boundary segregation, and mechanical properties were systematically analyzed. Moreover, the mechanisms by which TiC particles contribute to grain refinement, suppression of grain boundary segregation, and enhancement of hardness and wear resistance were discussed. The results demonstrate that TiC particles act as heterogeneous nucleation sites for α-Al within the Al-Cu-Mn alloys, leading to a refinement of grain size. As the TiC particle’s content increases, the grain size of the alloy drops at first and then elevates, transitioning from coarse dendritic crystals to fine equiaxed grains. At a TiC content of 1.3wt.%, the alloy exhibits the smallest grain size, reducing from 139±42 μm without TiC to 90±38 μm. Beyond this concentration, grain coarsening is observed. The incorporation of TiC particles effectively mitigates Cu segregation at grain boundaries, thereby enhancing the homogeneity of the Al-Cu-Mn matrix alloys. Additionally, the addition of TiC particles promotes hardness and wear resistance. Both hardness and wear resistance exhibit an initial increase followed by a decrease with increasing TiC content from 0 to 1.8wt.%.