Double cross-linked interpenetrating polymer network (IPN) hydrogels of sodium alginate and gelatin (SA/G) reinforced with 50 wt % cellulose nanocrystals (CNC) have been prepared via the freeze-drying process. The IPNs were designed to incorporate CNC with carboxyl surface groups as a part of the network contribute to the structural integrity and mechanical stability of the hydrogel. Structural morphology studies of the hydrogels showed a three-dimensional (3D) network of interconnected pores with diameters in the range of 10-192 μm and hierarchical pores with a nanostructured pore wall roughness, which has potential benefits for cell adhesion. Significant improvements in the tensile strength and strain were achieved in 98% RH at 37 °C for CNC cross-linked IPNs. The high porosity of the scaffolds (>93%), high phosphate buffered saline (PBS) uptake, and cytocompatibility toward mesenchymal stem cells (MSCs) are confirmed and considered beneficial for use as a substitute for cartilage.