Design/methodology/approach This study examines the mechanical properties of friction stir welded (FSW) dissimilar joints between IN625 and AISI316 alloys, with and without reinforcement by Al2O3 and TiO2 particles. The tensile strength, wear rate, coefficient of friction, microhardness and compressive strength of these joints were evaluated and compared to the base materials. Findings Results showed that the FSW process significantly improved the mechanical properties, with the particle-reinforced joints outperforming the non-reinforced ones. In particular, the IN625-AISI316/Al2O3 joint exhibited the highest tensile strength (690 MPa), lowest wear rate (1.92 × 10³ mm³/m) and the lowest friction coefficient (0.32). Microhardness testing revealed that the weld nugget (WN) region displayed the highest hardness (227 HV) due to grain refinement. The compressive strength of the IN625-AISI316/Al2O3 joint reached 1,583 MPa, the highest among all samples tested. These findings demonstrate the potential of using particle-reinforced FSW dissimilar joints for applications requiring superior mechanical performance, durability and wear resistance. Originality/value This study explores the enhanced mechanical and wear properties of FSW dissimilar joints between IN625 and AISI316 alloys, with and without Al2O3 and TiO2 nanoparticle reinforcements. Reinforced joints, particularly IN625-AISI316/Al2O3, showed superior tensile strength, wear resistance, hardness and compressive strength compared to non-reinforced ones. Grain refinement in the WN region contributed to increased hardness. These findings suggest that nanoparticle-reinforced FSW dissimilar joints can significantly improve durability and mechanical performance, making them ideal for demanding structural applications.