<p>¹³⁷Cs and ⁹⁰Sr are among the most hazardous radioactive isotopes released during the standard operation of nuclear reactors, as well as through nuclear accidents and weapons testing. Due to their high solubility, long half-lives, and strong environmental mobility, their removal from aqueous systems is essential for safe radioactive waste management. Inorganic layered materials have attracted increasing interest for this purpose because of their exceptional chemical, thermal, and radiolytic stability, high surface areas, and superior ion exchange capacities. This review summarizes findings from over 150 studies on the application of synthetic layered materials—including layered double hydroxides (LDHs), metal sulfide ion exchangers (MSIEs), MXenes, and insoluble acid salts—for the removal of Cs⁺ and Sr²⁺ from aqueous media. LDHs, particularly Mg–Al and Zn–Al types, exhibit strong uptake performance, especially when synthesized via hydrothermal or co-precipitation methods. MSIEs show high selectivity toward Cs⁺ even in the presence of competing ions, owing to their soft ligand frameworks. MXenes have emerged as a novel and highly tunable class of materials, with functionalization and interlayer modification playing a key role in enhancing sorption performance. Insoluble acid salts also offer promising uptake capabilities but are limited by low selectivity in acidic conditions. Overall, trends indicate a shift toward materials with modifiable interlayer spacing, surface functionality, and multi-ion selectivity.</p>