With the ongoing energy transition, the utilization of solar energy has become increasingly important. Photothermal conversion represents a key approach for harnessing solar energy, and nanofluids, owing to their excellent thermophysical properties, have shown great potential for enhancing photothermal conversion efficiency. This study investigates an aqueous-based titanium carbide (TiC) and silicon carbide (SiC) hybrid nanofluid, with a focus on its synergistic effects and underlying mechanisms in photothermal absorption. To address the issue of nanoparticle agglomeration in the base fluid, a biopolymer, bone glue, is employed as a dispersant. Its favorable biocompatibility ensures the long-term stability of the prepared nanofluid. Deionized water, as a commonly used base fluid, provides a pure reaction environment that facilitates the analysis of the influence of nanoparticles on the thermophysical properties of the fluid. By combining TiC and SiC nanoparticles, a synergistic enhancement effect is achieved. Experimental results demonstrate that at a concentration of 0.020%, the prepared hybrid nanofluid achieves a photothermal conversion efficiency of 94.7%, which is 20.5% higher than that of deionized water. Through detailed experimental characterization and mechanistic analysis, this study reveals the potential application of the hybrid nanofluid in solar photothermal conversion, providing both theoretical insights and experimental support for the development of efficient and environmentally friendly solar-absorbing materials.