¹³⁷Cs is one of the most intractable β-emitters which is commonly generated from nuclear weapons test and nuclear power station. Due to the nature of high solubility and mobility, the effective sequestration of ¹³⁷Cs ⁺ from radioactive waste solution is considered as a long-term challenge. In this work, a two-dimensional layered anion framework material (SZ-6) was synthesized through conventional solvothermal reaction and the Cs ⁺ removal properties were systematically investigated. Single Crystal X-ray Diffraction (SCXRD) analysis revealed that SZ-6 adopts layer packed structure with large tetramethylammonium cations loaded between the layers which is greatly beneficial to cation exchange process. Powder X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) confirmed the material with high purity and excellent hydrolytic stability. Batch experiments were used to investigate the adsorption behavior towards Cs ⁺ in aqueous solutions. The adsorption kinetics of SZ-6 could be achieved within 5 min, which is currently one of the fastest sorbents for the removal of Cs ⁺. Meanwhile, SZ-6 exhibits superior decontamination capability over a wide pH range from 4 to 12. Furthermore, it possesses marked selectivity in the presence of large excess of Na ⁺, K ⁺, Ca ²⁺ competing cations.