Abstract: To meet the growing demand for innovative high-performance green building materials in the construction industry, this study designs a novel sandwich panel composed of GFRP (glass fiber-reinforced polymer) skins and an aluminum honeycomb core filled with ultra-high performance recycled fine aggregate concrete (UHP-RFAC). The compressive and flexural behaviors of these panels were experimentally investigated, with emphasis on the effects of (1) GFRP skin thicknesses, (2) aluminum honeycomb core thicknesses, and (3) concrete infill on failure modes, compressive strength, and bending strength. Test results revealed that under axial compression, failure occurred in the core layer, whereas three-point bending tests induced failure in both the GFRP skins and the aluminum honeycomb. Filling the honeycomb with UHP-RFAC significantly enhanced the compressive and flexural strength of the panels. Moreover, increasing the thickness of either the GFRP skins or the honeycomb core further improved mechanical performance.