We propose a facile method for preparing novel poly(ethylene glycol) (PEG) shape-stabilized phase change materials (PCMs) using self-assembled network scaffolds formed by gels for thermal energy storage. 1,3:2,4-dibenzylidene sorbitol (DBS) is capable of self-organizing into 3-D nanofibrillar networks in organic solvents to form gels at relatively low concentrations. In this study, we induced the formation of such nanofibrils in PEG. After PEG is heated to its melting temperature, the DBS gels (nanofibrillar structures) can capture most of the molten PEG, significantly stabilizing the shape and preventing leakage. The fabricated PCMs can sustain their shape up to at least until 96 °C, as determined using rheological measurement. The PEG with a molecular weight of 8000 g/mol containing DBS systems exhibited the best thermal properties, including latent heat, leakage percentage and thermal conductivity, which could be useful in developing novel phase change materials for thermal energy storage.