Coastal erosion is a growing global concern, intensified by sea-level rise from thermal expansion and increasingly frequent, severe storms. While mangrove restoration is widely proposed as a natural defense, little attention has been given to identifying configurations that maximize protection. Therefore, this study aims to estimate the most effective mangrove’s configuration that can reduce wave height and mitigate coastal erosion maximally. To achieve this goal, a numerical model, designed to simulate wave and bed sediment evolution due to mangrove’s integration in coastal environments, is presented. The model couples the Nonlinear Shallow Water Equations with the Exner Equation, solved using the Finite Volume Method with a wet–dry algorithm on a staggered grid. Validation against experimental datasets confirms its accuracy in reproducing wave and sediment dynamics. Following validation, the model is employed to simulate a range of scenarios with varying parameters. Sensitivity analyses are conducted to investigate the influence of mangrove length, porosity, and location, on wave reduction and erosion control. It was found that increasing mangrove length and density effectively reduced wave transmission and erosion, confirming their role in coastal protection. However, optimal configuration depends on local bathymetry and ecological conditions to ensure mangrove survival and performance. Ultimately, the findings are expected to provide guidelines for identifying the most effective characteristics of mangrove to reduce wave height and control coastal erosion.