V.A highly efficient, bio-ecofriendly, and transparent flame retardant (FR) for cotton fabric was developed and deposited onto the cellulose skeletal structure of cotton fabric through a one-pot sol-gel process. The flame retardant functional coating is composed of ammonium polyphosphate (APP), guar gum (GG), citric acid (CA), and a negligible amount of catalyst. Cotton fabrics were impregnated with different concentrations of ammonium polyphosphate and guar gum, with citric acid as a crosslinking agent. The overall crosslinking and grafting process was proven by FTIR and XPS. Based on the results, the designed coating exhibits over 90 % transmittance in the visible region. A 15 g/m2 flame-retardant coating induces excellent flame retardant efficiency at ultra-low flame-retardant concentrations of less than 6.25 wt%. Only a 5.25 wt% flame retardant concentration demonstrated condensed phase action, which resulted in 58.5 % and 73.6 % reductions in the pHRR and THR, respectively. Moreover, the limiting oxygen index (LOI) value showed a 74 % increase. The mechanical performance of FR coated cotton fibers was slightly reduced.