Bio-based compounds have become the focus of development for next-generation materials. The polyphosphated structure and availability of phytic acid has sparked an interest to understand its properties and apply it to making fire-retardant fabrics. However, its degradative effect on natural fibers sets limitations to its potential uses. In this study, we unveiled a new dimension to explore with phytic acid: cellulose fiber foams. Phytic acid enabled synergistic foaming behaviour with carboxymethyl cellulose albeit promoting issues in long-term foam stability. Adding cellulose fibers to this mixture and drying at 160 °C produced solid foams with increased compressive strength and stiffness; comparable to the commonly used cellulose cross-linker, citric acid. The reduced contact area in low-density fiber networks allowed the cross-linking between phytic acid and the fiber network to mitigate structural weakening due to fiber degradation. Imaging also revealed the formation of a film encompassing fiber bonds; attributed to the strong interaction between phytic acid and carboxymethyl cellulose. Furthermore, phytic acid imparted self-extinguishing fire-retardant properties to the cellulose fiber foams measured using thermogravimetric analysis and cone calorimetry. This work showcases a simple new application for phytic acid without the use of catalysts or solvents. It serves to encourage further development of green practices to continuously challenge the industrial landscape.