Geosynthetic-reinforced and pile-supported (GRPS) embankments are becoming more popular as a solution for addressing soil structural instability. The interaction between the geosynthetic-pile-subsoil-embankment elements is crucial to the load transfer mechanism and performance of GRPS embankments. Several analytical models for GRPS embankment design have been proposed, but their performance and applicability still require further validation. This research presents a three-dimensional numerical investigation of the load transfer mechanism of GRPS embankments using the finite difference approach, considering the combined interaction between the soil embankment, geosynthetics, pile, and subsoil. The importance of these crucial aspects in the GRPS embankment design technique is highlighted, as well as their influence and sensitivity. The following elements, in descending order, influence the load and settlement efficacies of the GRPS embankments: soft soil stiffness, embankment height, geosynthetic stiffness, and embankment soil density, according to this research. Furthermore, the use of geosynthetics reduces differential settlements and mitigates soil yielding above the pile heads. The numerical findings are then compared to four well-known design standards, with the subsurface stiffness, geosynthetic stiffness, embankment height, and fill soil density all being varied simultaneously to measure their performance. The findings of the comparison revealed that these techniques differ greatly in their ability to forecast load efficacy and differential settlement. Depending on the geometric properties of the embankment and material properties, all of the selected design methods produce over-predictions or under-predictions.