Purpose <p>The study aims to enhance the seismic stability and cost efficiency of reinforced earth retaining walls by integrating geo-synthetics and employing advanced optimization techniques. Traditional reinforced walls often face structural instability under seismic loading, leading to excessive deformation and high construction costs. Therefore, this work focuses on optimizing the design parameters of geo-synthetic reinforced soil retaining walls (GRS-RW) to achieve improved seismic performance with minimal material and economic expenditure.</p> Methods <p>A novel Hippopotamus Optimization (HO) algorithm is developed and implemented in MATLAB to optimize the size and cost of GRS-RW systems. The proposed approach is evaluated against well-established optimization methods such as Particle Swarm Optimization (PSO), Biogeography-Based Optimization (BBO), and Harmony Search Algorithm (HSA). The analysis considers various seismic acceleration coefficients (kh) ranging from 0 to 0.2 to assess the structural response under dynamic loading.</p> Results <p>Simulation results indicate that the HO algorithm effectively minimizes construction cost while improving wall stability. The study reveals that extending the anchoring length of the geo-synthetic reinforcement by 28.5% enhances overall wall stability. Furthermore, as seismic acceleration increases from 0 to 0.2, the reinforcement force exhibits a 23.6% rise, indicating adaptive structural resilience.</p> Conclusion <p>The integration of geo-synthetics combined with the HO optimization technique offers a robust and cost-effective solution for improving the seismic stability of reinforced earth retaining walls, outperforming existing optimization algorithms in both accuracy and efficiency.</p>