Lightweight ablative thermal protection materials (TPMs) with excellent ablation, thermal insulation, and anti-oxidation are urgently needed for aerospace vehicles. Herein, a distinct strategy was proposed that uses aerogel-like polysiloxane (SiA) as a matrix, and carbon-bonded carbon fiber (C/C) composite as reinforcement to construct a lightweight SiA impregnated C/C (C/C-SiA) composite, through vacuum impregnation, sol-gel, and atmospheric pressure drying. The intriguing characteristics including high mechanical strength and stiffness, thermal stability and oxidation resistance, and a low thermal conductivity of 0.063 W/(mK) were integrated into the low-density (0.238-0.306 g/cm(3)) C/C-SiA. The synergistic effect originated from pyrolysis products of SiA including silicon oxycarbide ceramic to inhibit oxygen diffusion and pyrolysis gas to retard convective heat transfer, the high emissivity surface re-radiation to dissipate heat and transverse thermal conductivity to regulate heat transfer by C/C, enables C/C-SiA to deliver remarkable thermal insulation performance (20 mm backside temperature below 40 degrees C on a heating plate for 1800 sec) and ablation resistance (near-zero surface recession of 0.18 mu m/s exposed to 1300 degrees C flame for 1200 sec). The ceramifiable strategy can be extended to other preceramic polymers, such as polycarbosilane, polysilazane, and ZrO2 precursor, which may open a new avenue for improving lightweight ablative TPMs.