Geocells are three-dimensional, interconnected cellular geosynthetics widely used to enhance the overall strength of soils. Their foldable structure can cause variations in pocket shape during installation, depending on the extent of extension. Understanding the impact of these shape variations is essential for optimizing reinforcement efficiency and reducing the associated geocell application costs. The aspect ratio, defined as the ratio of the cell's transverse (welded) axis to the longitudinal (wall summit) axis, is proposed to evaluate the degree of extension of the most commonly utilized honeycomb-shaped geocell. A coupled continuum-discontinuum numerical method was employed to investigate the behavior of honeycomb-shaped geocell reinforced soils across various aspect ratios under confined compressive loading. The simulation results indicate that a geocell with an aspect ratio of 1.0 exhibits optimal reinforcement efficiency, and whereas reinforcement efficiency decreases as the aspect ratio deviates from 1.0 causing pocket geometries to flatten. The superior performance of rounded geocells is attributed to their enhanced ability to promote load-bearing in strong contact subnetworks. This results in denser packing structures, higher contact force anisotropy from a microscopic perspective, and greater confinement capacity against deformation from a macroscopic perspective.