In this study, the hollow glass microsphere (HGS)/stearic acid (SA) composites were prepared as form stable phase change materials (FSPCMs) for thermal energy storage via directly impregnation. In prepared FSPCMs, SA acted as the phase change substance and the HGS functioned as the supporting materials to prevent the leakage of melted SA. The special structure and large surface of HGS had strong absorption ability for SA. The chemical structure, surface morphology, crystalline properties, phase change properties, thermal reliability and stability of prepared FSPCMs were extensively studied by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermal cycling test and thermogravimetric analysis (TGA), respectively. FTIR results showed that only physical interaction occurs between HGS and SA, and the SEM images showed the SA is adhered on the surface and internal surface of HGS through physical interaction. The XRD pattern exhibited that the crystalline properties of FSPCMs are not affected by the introduction of HGS. FSPCMs also exhibited good phase change properties with the latent heat in the range of 48.77–133.8 J g−1 and the phase change temperature in the range of 50.20–51.54 °C, and the supercooling degree was lower than 2 °C. The special structure of HGS imparted FSPCMs with good thermal reliability reflected by slightly variation of latent heat and phase change temperature after 100 thermal cycles. TGA results showed the FSPCMs have good thermal stability, which will meet the requirement of application. In conclusion, the prepared FSPCMs had great value in the field of thermal energy storage.