Dams are highly important structures used for irrigation, flood control, power generation, water supply, and other purposes. Since dam construction is both costly and time-consuming, optimizing dam designs to minimize construction costs is essential, yet challenging. This study aims to optimize the design of a homogeneous earth dam with a rock toe by considering its construction cost. In this type of dam, the cost of rockfill operations at the dam toe is typically 2 to 20 times higher than that of earthwork operations in the dam body. It should also be noted that seepage through the dam body must be minimized to prevent structural damage and excessive water loss. This can generally be achieved by increasing the dimensions of the dam body.The proposed design considers the hydraulic gradient criterion as well as the stability of the upstream and downstream slopes under full-reservoir, empty-reservoir, and rapid-drawdown conditions. To solve this multi-objective optimization problem involving nonlinear constraints, the Multi-Objective Particle Swarm Optimization (MOPSO) algorithm was employed. To derive appropriate equations for applying the constraints, more than 350 dam models were developed and analyzed using GeoStudio software. The constraint equations were subsequently obtained through regression analysis. These equations were then incorporated into the aforementioned metaheuristic algorithm to optimize the dam design. The results demonstrate that the proposed method is efficient and provides satisfactory solutions.