Abstract: Carbon-based light-absorbing materials exhibit broad application prospects in fields such as photothermal conversion, photodetection, and photocatalysis due to their excellent optical stability, adjustable microstructure, and good environmental compatibility. Vertical graphene (VG) has potential applications as a light-absorbing material owing to its unique 3D nanostructure and π-band optical transition properties. However, the morphology of VG and that of the substrate directly influence its light absorption performance. In this study, a vertical graphene/surface-modified nickel (VG/smNi) composite light-absorbing material was successfully prepared via the synergistic regulation of Ni substrate surface modification and VG growth process. The structure and properties of the composite material were systematically characterized by SEM, Raman, surface profiling tests, and UV-Vis reflection spectroscopy. The results revealed that wall-like VG facilitates the formation of light traps, thereby enhancing absorption performance. Additionally, the surface of the surface-modified nickel substrate exhibits a porous microstructure, providing an excellent surface microstructure for the growth of VG and the optimization of its light absorption. Moreover, UV-Vis reflection spectroscopy demonstrates that the VG/smNi composite structure exhibits a minimum reflectance as low as 0.34% at a wavelength of 646 nm, with reflectance remaining below 1% across an incident angle range of 0° to 55°. This study offers new insights and experimental evidence for optimizing the performance of carbon-based light-absorbing materials.