Recently, three-dimensional (3D) scaffolds produced using poly-Pickering high internal phase emulsions (polyHlPEs) technology are particularly attractive in biomedical application. However, until now the most investigated polyHIPEs are hydrophobic composites originating from synthetic polymers. Here we present an investigation of a hierarchical porous protein scaffold templated from oil-in-water (O/W) HIPEs costabilized by fully natural materials, gelatin, and gelatin nanoparticles. Fairly monodispersed gelatin nanoparticles were first synthesized through a two-step desolvation method, and then they were used as emulsifiers together with gelatin to fabricate stable HIPEs with adjustable droplet size distribution and rheology. Monolithic scaffolds were formed by cross-linking the HIPEs with polymers as low as 2.5 wt % in the continuous phase, which appropriately presented a general high porosity and had an interconnected porous morphology with smooth pore walls and textured structures. Furthermore, the scaffolds were degradable and showed reasonably good biocompatibility; L929 cells could adhere to the surface of the materials and exhibited intensive growth and well-spread morphology. This hierarchical porous protein scaffold could, therefore, have important application as a 3D scaffold that offers enhanced cell adhesion and functionality.