Energy efficient buildings require novel thermal insulators accompanied by lightweight, mechanically robust, fire resistant, and low thermal conductivity. Ceramic fibrous aerogels have emerged as promising candidates, however it’s difficult for these materials to achieve exceptional mechanical and thermal insulation performance simultaneously. Here, we demonstrate a unique semi-template method to fabricate biomimetic-architectured silica/carbon dual-fibrous aerogel with robust mechanical performance. Specifically, aerogels with honeycomb-like cellular and nanofiber/nanonet cell wall were constructed by freeze-drying the homogeneous dispersion of SiO₂ nanofibers and cellulose nanofibers co-suspensions. It is worth noting that the biomimetic structure has been perfectly inherited even subjected to high-temperature carbonization. As a result, the excellent structural stability brought by the novel structure enables the aerogel to completely recover under large compression and buckling strain of 80%, and exhibit robust fatigue resistance over 200,000 cycles. More importantly, the aerogels exhibit ultralow thermal conductivity (0.023 W·m⁻¹·K⁻¹), superior flame retardancy, together with excellent thermal insulation performance over a wide temperature ranging from −196 to 350 °C. The fabrication of such materials may provide new ideas for the development of next-generation thermal insulators for harsh conditions.