Recent investigations have increasingly concentrated on the advancement of the in-situ technique with the objective of enhancing the wettability, uniformity, and thermodynamic stability of reinforcement particles within the aluminum matrix. In this study, stir casting was employed to fabricate in-situ composites based on Al alloy A356 reinforced with the Al₃Ni phase, incorporating different weight fractions of pure Ni powder (5 wt%, 10 wt%, and 15 wt%). Several evaluations, including microhardness measurements, microstructural analysis, and corrosion assessments, were conducted on the developed in-situ composites. The microstructural characteristics of Al alloy A356 revealed the formation of the in-situ Al₃Ni intermetallic phase within the matrix, along with a notable refinement of the A356 aluminum matrix. The hightlight findings indicated that the presence of Al₃Ni particles enhanced both hardness and resistance to corrosion; consequently, the in-situ composite with 15 wt% Ni exhibited the maximum hardness value (152 HV) compared with the base alloy hardness (76 HV). A pronounced improvement in corrosion resistance was particularly evident in composites containing 5 wt% Ni. It was shown that the 5% Ni composite exhibited the best corrosion resistance (97% improvement) as compared to the base alloy and other composites, which decreases with increasing Ni particles.