<p>Poly(vinyl chloride) (PVC) materials are produced with high smoke and toxic gases during combustion, when commercial flame-retardant additives are incorporated. Here, rare-earth yttrium stannate (Y₂Sn₂O₇), which is superior to commercial flame retardants, was designed to enhance the smoke suppression and toxicity reduction performance of PVC materials without damaging their mechanical properties. After the addition of 15 wt% Y₂Sn₂O₇ (PVC/Y₂Sn₂O₇), the PVC composites achieved a V-0 rating, whereas the pure PVC material achieved a V-2 rating. The peak heat release rate of PVC/Y₂Sn₂O₇ composite was reduced from 282.7 kW/m² (pure PVC) to 243.6 kW/m². In addition, the maximum smoke density (Ds-max) of PVC/Y₂Sn₂O₇ was 263 m²/m², a decrease of 48.5% compared to pure PVC materials (511 m²/m²), indicating its outstanding ability for smoke suppression. Compared to Sb₂O₃, Y₂Sn₂O₇ can effectively reduce the release of the toxic gas CO (decreasing by 37.5%). Furthermore, the tensile strength of PVC can reach as high as 16.1 MPa. Compared with five widely used commercial flame retardants, Y₂Sn₂O₇ demonstrates superior performance, positioning it as a promising alternative to prospective candidates. Therefore, this study developed a rare-earth flame retardant and offers a promising design to improve the fire safety of PVC composites.</p>