<p>Triply periodic minimal surface (TPMS) structures have unique geometric features mainly periodic cell structures, zero mean curvature and larger surface area to volume ratio. Due to these characteristics, TPMS structures exhibit superior mechanical properties, including high strength-to-weight ratio, high stiffness and excellent energy absorption characteristics. This study investigates the effect of relative density on mechanical properties and energy absorption capabilities of strut-based uniform and density gradient Gyroid structures fabricated using the fused filament fabrication (FFF) 3D printing technique. The study addresses stress–strain behavior, deformation mechanisms and energy absorption characteristics to evaluate the influence of relative density variations. Also, the experimental results are compared with Gibson–Ashby model equations. Results indicate that uniform Gyroid structures exhibit significant improvements in compressive strength (160.59%) and stiffness (184.69%) with increasing relative density, demonstrating stable plateau regions and global deformation behavior. While, density gradient Gyroid structures exhibit a moderate increase in compressive strength (31.21%) but a substantial enhancement in stiffness (105.51%), attributed to their progressive layer-wise deformation. Additionally, the specific energy absorption (SEA) of gradient structures outperforms than uniform structures by 157.05%, highlighting their superior energy absorption capabilities. The experimental results are consistent with the Gibson–Ashby model, demonstrating its prediction accuracy for Gyroid structures. These findings highlight the prospective benefits of gradient Gyroid structures for applications like impact protection, medicinal scaffolds and aerospace components which require optimal mechanical performance and energy dissipation.</p>