Abstract <p>Aerogels remain a focal point for researchers seeking to tackle environmental and energy challenges through innovative thermal insulation solutions. Designing and acquiring lightweight biobased aerogels that possess flexibility and thermal insulation represent a key future direction. Herein, taking advantage of synergistic assembly of xanthan gum (XG) and konjac glucomannan (KGM), and a novel biobased aerogel (XG/KGM@F) was fabricated and scaffolded by multiscale cellulose fibers (MCFs) through vacuum freeze-drying technology. The structural characterization demonstrates that the synergy of MCFs and polysaccharides forms a robust hierarchical network within the aerogels, significantly enhancing their mechanical resilience. The XG/KGM@F aerogels exhibit remarkable thermal insulation properties with a temperature difference (Δ<i>T</i>) exceeding 60&#xa0;°C for a long time between the top and bottom surfaces of the aerogels. With an ultra-low density of 3.97&#xa0;mg&#xa0;cm⁻³ and a thermal conductivity of 0.0288&#xa0;W&#xa0;m⁻¹&#xa0;K⁻¹, the XG/KGM@F demonstrates its potential for applications necessitating lightweight and sustainable thermal insulation. This study not only advances the design of biobased aerogels but also provides a scalable and eco-friendly strategy for developing high-performance insulation materials, aligning with global sustainability goals in packaging, construction, and energy conservation.</p> Graphical Abstract <p></p>