In this research work, a three dimensionally (3D) interconnected porous polystyrene-carbon nanotubes (PS-CNT) polyHIPE foam was developed as a phase change material (PCM) scaffold for photo-to-thermal energy storage applications. Structural and thermal properties of the novel phase change composite were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) spectroscopy, ultraviolet-visible diffused reflectance spectroscopy, differential scanning calorimetry (DSC) analysis, and laser flash analysis. The paraffin/PS-CNT composite containing 1 wt% CNTs exhibited a thermal conductivity as high as 0.39 Wm(-1) K-1, 1.62 fold higher than that of pure paraffin. The highly porous structure of the prepared foam led to a high PCM loading of 82.5%, a high latent heat of 119.3 J g(-1) and a melting point of 56.88 degrees C. The prepared composite preserved its stable thermophysical properties after 100 melting/solidification cycles. The enthalpy of paraffin increased about 3.5% after infiltrating into the PS-CNT polyHIPE foam. Further, the composite displayed excellent shape stability, which prevented the leakage of phase change material during phase transitions. Incorporation of carbon nanotubes in the polyHIPE foam led to black color of the composite leading to an increase in the light absorbance efficiency and especially the light-to-thermal energy conversion efficiency (90%).