Rigid polyurethane foam (RPUF) has attracted great attention as an insulation material, but its inherent flammability restricts its practical application. Developing a sustainable fire-retardant strategy that can improve its fire safety is particularly desirable and challenging. Herein, novel fire-retardant hydrogel coatings based on polyvinyl alcohol (PVA) and borax are proposed and applied in RPUF, and the self-healing, recyclability and flame retardant properties of the coatings are investigated. The dynamic and reversible cross-linked networks based on the borate ester bonds and hydrogen bonds endow the hydrogels with excellent repairability, recyclability, and elasticity. Compared with a neat RUPF, the coated RPUF exhibited improved fire-retardant properties without the inherent advantages being influenced and can be reflected by the 8% increase in the limiting oxygen index (LOI), 20% reduction in total heat release (THR), and 25% decrease in total smoke production (TSP) with the coatings, along with a rapid self-quenching behavior. The novel hydrogel coatings provide a new strategy for the development of flame-retardant coatings, demonstrating the potential of the next generation of self-healing hydrogel coatings to reduce the fire risk of the RPUF.