Over 40 % of global energy consumption is attributed to thermal regulation in buildings, highlighting the imperative for low-carbon structures. Aerogel insulation materials with low thermal conductivity show promise for energy-saving buildings. However, their widespread adoption is hindered by inadequate mechanical robustness, stability, and fire resistance. Herein, inspired by plant root-soil structures, mechanically robust Poly-p-phenylene benzoxazole (PBO) nanofiber-reinforced silica aerogels (BNFSi) are designed and synthesized via a dimension-upgrading strategy. The optimized BNFSi are characterized by Compressive strength (3.2 MPa). Additionally, the aerogel demonstrates several outstanding properties, such as low thermal conductivity (27.3 mW m⁻¹ K⁻¹), superior flame retardancy, high mass retention rate (79.7 %), high reflectivity in the visible to near-infrared spectrum (∼ 92 %), and inherent super-hydrophobic surface with a 150.3° water contact angle, indicating self-cleaning potential. The biomimetic-designed structure resolved the inherent brittleness of the silica network while inducing fire-resistant and ideal insulating performance, thus offering a promising avenue for advancing energy-conserving buildings, aligning with the objectives of next-generation eco-conscious construction.