This study presents a novel method for additive manufacturing (AM) of nanocellulose aerogels with structure-oriented thermal, mechanical, and biological properties. The approach involves using direct ink writing (DIW) to 3D print intricate, high-fidelity macroscopic cellulose aerogels. By incorporating fibers of different length scales into hydrogel inks, the resulting aerogels exhibit tunable anisotropic mechanical and thermal characteristics. The alignment of nanofibers significantly enhances mechanical strength and thermal resistance, leading to higher thermal conductivities in the longitudinal direction (65 mW m⁻¹ K⁻¹) compared to the transverse direction (24 mW m⁻¹ K⁻¹). Rehydration of printed cellulose aerogels for biomedical applications preserves their high surface area (≈300 m² g⁻¹) while significantly improving mechanical properties in the transverse direction. These printed cellulose aerogels demonstrate excellent cellular viability (>90% for NIH/3T3 fibroblasts) and exhibit robust antibacterial activity through in situ-grown silver nanoparticles. The study highlights the use of cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs) in different concentrations to achieve desired properties. The rheological properties of the inks were adjusted by tuning the concentrations of each phase, allowing for precise control over the printing process. The alignment of CNFs and CNCs during extrusion leads to anisotropic properties, with the alignment doubling the tensile strength in the longitudinal direction and increasing thermal resistance in the transverse direction. The printed aerogels withstand cycles of drying and rehydration while maintaining good pore structure and improved mechanical properties. The aerogels were tested for their thermal insulation properties, showing a thermal conductivity of 65 mW m⁻¹ K⁻¹ in the longitudinal direction and 24 mW m⁻¹ K⁻¹ in the transverse direction. The aerogels also demonstrated excellent biocompatibility, with high cell viability and antibacterial activity. The study concludes that the 3D printing technology is a versatile and scalable approach to fabricating cellulose aerogels with tailored properties and geometries for a wide range of applications, especially in thermal insulation and biomedical fields.This study presents a novel method for additive manufacturing (AM) of nanocellulose aerogels with structure-oriented thermal, mechanical, and biological properties. The approach involves using direct ink writing (DIW) to 3D print intricate, high-fidelity macroscopic cellulose aerogels. By incorporating fibers of different length scales into hydrogel inks, the resulting aerogels exhibit tunable anisotropic mechanical and thermal characteristics. The alignment of nanofibers significantly enhances mechanical strength and thermal resistance, leading to higher thermal conductivities in the longitudinal direction (65 mW m⁻¹ K⁻¹) compared to the transverse direction (24 mW m⁻¹ K⁻¹). Rehydration of printed cellulose aerogels for biomedical applications preserves their high surface area (≈300 m² g⁻¹) while significantly improving mechanical properties in the transverse direction. These printed cellulose aerogels demonstrate excellent cellular viability (>90% for NIH/3T3 fibroblasts) and exhibit robust antibacterial activity through in situ-grown silver nanoparticles. The study highlights the use of cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs) in different concentrations to achieve desired properties. The rheological properties of the inks were adjusted by tuning the concentrations of each phase, allowing for precise control over the printing process. The alignment of CNFs and CNCs during extrusion leads to anisotropic properties, with the alignment doubling the tensile strength in the longitudinal direction and increasing thermal resistance in the transverse direction. The printed aerogels withstand cycles of drying and rehydration while maintaining good pore structure and improved mechanical properties. The aerogels were tested for their thermal insulation properties, showing a thermal conductivity of 65 mW m⁻¹ K⁻¹ in the longitudinal direction and 24 mW m⁻¹ K⁻¹ in the transverse direction. The aerogels also demonstrated excellent biocompatibility, with high cell viability and antibacterial activity. The study concludes that the 3D printing technology is a versatile and scalable approach to fabricating cellulose aerogels with tailored properties and geometries for a wide range of applications, especially in thermal insulation and biomedical fields.