This study presents lightweight, anisotropic foams composed of nanocellulose and graphene oxide, enhanced with sepiolite nanorods, which exhibit excellent thermal insulation and fire-retardant properties. The foams, produced through freeze-casting of colloidal suspensions, have a thermal conductivity of 15 mW m⁻¹ K⁻¹, significantly lower than traditional materials like expanded polystyrene (EPS). They also demonstrate high mechanical strength and good fire resistance, with a limiting oxygen index (LOI) of 34, indicating superior flame retardancy. The foams retain over half their initial strength at 30°C and 85% relative humidity, making them suitable for applications requiring both thermal insulation and structural integrity. The combination of nanocellulose, graphene oxide, and sepiolite provides a lightweight, renewable material with exceptional thermal and mechanical properties, offering a promising alternative to conventional insulation materials. The study highlights the potential of nanoscale engineering in developing sustainable, high-performance materials for energy-efficient buildings.This study presents lightweight, anisotropic foams composed of nanocellulose and graphene oxide, enhanced with sepiolite nanorods, which exhibit excellent thermal insulation and fire-retardant properties. The foams, produced through freeze-casting of colloidal suspensions, have a thermal conductivity of 15 mW m⁻¹ K⁻¹, significantly lower than traditional materials like expanded polystyrene (EPS). They also demonstrate high mechanical strength and good fire resistance, with a limiting oxygen index (LOI) of 34, indicating superior flame retardancy. The foams retain over half their initial strength at 30°C and 85% relative humidity, making them suitable for applications requiring both thermal insulation and structural integrity. The combination of nanocellulose, graphene oxide, and sepiolite provides a lightweight, renewable material with exceptional thermal and mechanical properties, offering a promising alternative to conventional insulation materials. The study highlights the potential of nanoscale engineering in developing sustainable, high-performance materials for energy-efficient buildings.