The present study has demonstrated the flame retardancy effect of Banana pseudostem (BPS) as plant wastes at different concentrations on bleached and mercerized Egyptian cotton fabric made of Giza 90. Alkaline method was used to produce the extract BPS. The cotton fabric after the treatment was found to produce stable natural semi kaki color. Flame retardant properties of both the untreated and the treated cotton fabrics were analyzed in terms of limiting oxygen index (LOI), horizontal and vertical flammability. The control and the treated cotton fabrics were examined using FTIR, thermo-gravimetric analysis, mechanical properties, and color components analysis. The results revealed that, the treated cotton fabrics were found to have good flame retardant property of LOI at BPS concentration 10% compared to the control fabrics. In the vertical flammability test, the treated fabric showed flame for a few seconds and then got extinguished. In the horizontal flammability test, the treated fabric showed no flame, but was burning with a propagation rate of 7.5 mm/min, which was almost 10 times lower than that noted with the control fabric. The results revealed that, there was no significant degradation in mechanical strengths. Based on the results, the mechanisms of formation of natural color on the cotton fabrics using the proposed BPS treatments have been postulated.