Abstract: To optimize the mechanical and tribological properties of 7075Al alloy, a multi-pass friction stir processing technique was employed to fabricate HEAp–SiCp/7075Al composites with varying SiC particle contents. The influence of SiC content on the forming quality, interfacial characteristics, mechanical properties, and tribological behavior of the composites was investigated. The results indicate that at a SiC mass fraction of 2%, the reinforcing particles are uniformly dispersed in the nugget zone and tightly bonded to the matrix interface. With increasing SiC content, agglomeration becomes more severe and dispersion uniformity decreases. Microhardness exhibits an increasing trend with SiC content, with average nugget-zone hardness values reaching 150.97 HV, 160.96 HV, and 163.71 HV for the 2%, 5%, and 10% SiC specimens, respectively. In contrast, the tensile properties show the opposite trend;the 2% SiC specimen exhibits the best ultimate tensile strength of 416.5 MPa, attributed to aggravated agglomeration at higher contents. Fracture analysis reveals a ductile-brittle mixed mode, and as the SiC content increases, the dominant fracture mechanism shifts from particle fracture to interfacial debonding and agglomeration. Tribological performance significantly improves with the increase in SiC content, with the 10% SiC specimen exhibiting the smallest wear scar depth and the best wear resistance. Overall, the uniform dispersion of reinforcing particles plays a significant role in tuning the mechanical properties, and the synergistic reinforcement of an appropriate amount of SiC and high-entropy alloy (HEA) enables a comprehensive improvement in both strength and wear resistance of the composite. These findings provide experimental evidence and theoretical guidance for the composition optimization and process design of HEA particle-reinforced aluminum matrix composites.