To impart epoxy resin (EP) with excellent flame retardancy and smoke suppression, we prepared a novel inorgianic-organic nanocomposite flame retardant, zinc ferrite@polyphosphazene (ZF@PZS). The inorganic zinc ferrite plays a role in catalytic carbonization, improving char yields. The organic polyphosphazene helps zinc ferrite improve its compatibility and flame retardancy. Through synergistic effects, ZF@PZS exhibited excellent flame-retardant and smoke-suppression properties in the EP matrix. Compared to neat EP, the limiting oxygen index of the epoxy with 5 phr ZF@PZS increased from 24.6 % to 32.1 % and reached UL94 V-0 rating; the peak heat release rate, peak smoke production rate, and carbon monoxide production of EP composites also decreased by 37 %, 50 %, and 39 %, respectively. Condensed and gas phase analysis indicated that ZF@PZS helps epoxy generate more dense, stable, rigid residues and less pyrolysis volatile products, improving flame retardancy compared to ZF and PZS alone. Besides, the storage modulus of the composite was increased.