In an era of growing environmental awareness, advanced cellulose-based foams are urgently needed as sustainable alternatives to petroleum-based foams. Currently, the gel process involving dynamic covalent bonds, formed by borate (B) and tannin (T), has gained significant attention in polymer network design and engineering. These bonds can reversibly break and reorganize in response to external stress stimuli. Meanwhile, with the aid of foaming templates, the dynamic covalent network effectively traps air bubbles within the foam, preventing structural collapse caused by high surface tension during water evaporation. Herein, a facile strategy is proposed for fabricating 3D continuous cellulose-based foam with distinct lamellar structure by hierarchical assembly of cellulose fibrils and T/B complex via oven drying. The surface chemistry and interfacial interactions between the T/B complex and the influence of T/B complex on the micromorphology and hierarchical architecture of the foam was investigated. By incorporating cationic cellulose fibrils (CCNF), the T/B complex can be assembled on the surface of wood cellulose fibers by electrostatic attraction and hydrogen bonding. The formation of reversible covalent bonds of T/B complex imparts shear-thinning and self-healing properties to the system, thereby ensuring foaming efficiency and facilitating the formation of solid foams by oven drying. Moreover, the increased tannin content in the T/B complex reduces foam density but increases the normalized strength of the T/B foam by approximately 50% – 80% with tannin additions ranging from 2.5 -10%. Moreover, the pH-responsive and dynamically tunable nature of the prepared T/B complex can further provide active sites for metal ions (Fe3+, Cu2+, and Ag+) coordination, resulting in long-term antimicrobial behaviors. This study demonstrates a green and scalable strategy for producing customizable foam by the hierarchical assembly of cellulose fibrils and the T/B complex in biocomposite foam, opening new possibilities for fabricating functional foam materials.