This report discusses in detail about the Fire retardant (FR) characteristics of polyvinyl alcohol (PVA) matrix fabricated by impregnating zinc borate nanoparticles (ZB Nps) as FR with trace amounts of copper chloride/aluminum chloride by solvent casting method. ZB Nps prepared by co-precipitation method are characterized using XRD, FTIR, SEM, TEM, etc. XRD pattern revealed the crystal geometry of ZB Nps and SEM and TEM micrographs depict a rod-like structure with 300–400[Formula: see text]nm size. Appropriate amount of ZB Nps and transition metal salts are mixed with PVA in aqueous medium and thin film samples are obtained by solvent casting method. The vibrational spectra, thermal stability and flammability of the polymeric composites are characterized using FTIR, TG/DTA and Flammability tester, respectively. FTIR spectra confirm the existence of ZB Nps in the prepared polymer composites. TG/DTA studies revealed higher degradation temperature and thermal stability of polymer composite over pure PVA. The limiting oxygen index (LOI) test presented a convincing account about the improved FR nature of obtained polymer nano composite with a significant LOI of 56% compared to virgin polymer which have LOI of 19.6%.