<p>This study presents the development and characterization of a functionally graded metal matrix composite (FG-MMC) leaf spring plate fabricated using Al2024 alloy reinforced with nickel (Ni) and subjected to T3 heat treatment to enhance mechanical properties. The leaf spring design incorporates a gradient in Ni content, with 10 wt.% Ni at the center and 1 wt.% Ni at the ends, optimizing strength distribution based on load-bearing requirements. The stir casting technique was employed for fabrication, followed by heat treatment to refine the microstructure and improve mechanical performance. Characterization involved tensile testing, Charpy impact testing, Vickers hardness testing, and microstructural analysis using SEM. The results indicate that T3 heat treatment significantly enhances tensile strength, hardness, and impact resistance, with the center region exhibiting superior mechanical properties due to higher Ni reinforcement. FEA of tensile specimens confirms the experimental findings, with a strong correlation between predicted and measured stress–strain behavior. This research demonstrates that a functionally graded Al2024-Ni composite leaf spring with T3 heat treatment offers improved structural integrity, making it a promising alternative for automotive and aerospace applications.</p>