The effective capture of radioactive iodine vapor is crucial for radiation safety during spent fuel reprocessing. However, current materials used for iodine vapor capture have limitations such as low adsorption efficiency and poor stability, which hinder the effectiveness. To address this issue, an efficient, stable, recoverable and heterogeneous MOF-on-MOF [NH2-MIL-101-on-NH2-UiO-66] adsorbent was prepared using the epitaxial growth strategy. The adsorbent was extensively characterized with various technologies including FT-IR, XPS and XRD, and batch experiments were conducted to evaluate the performance in iodine gas adsorption. Results showed that the adsorption capacity of NH2-MIL-101-on-NH2-UiO-66 reached 1930 mg/g at 80 °C and ambient pressure, outperforming the parent MOFs, with a 20–33% higher adsorption rate and a 1.52–2.74 times higher adsorption capacity. Notably, the adsorbent exhibited superior performance compared to commercial silver-exchanged zeolite and other MOFs adsorbents. The excellent adsorption performance of this adsorbent can be attributed to its abundant adsorption sites and well-defined pore structure. Additionally, the adsorbent displayed good thermal stability, withstanding temperatures up to 360℃. Overall, this study provides a highly effective material for iodine vapor adsorption and contributes to the understanding of novel MOF-on-MOF architectures and the applications.