Polysaccharide-based hydrogel capsules with interconnected inner membranes have been prepared. The obtained capsules have a multi-layer internal structure composed of many invaginations of interconnected hydrogel membranes as mimics of the cristae in mitochondria. These cristae-like internal membranes endow the capsules with high specific area, which makes the capsules ideal supporting materials for catalytic species such as metal nanoparticles and enzymes.