Innovation of 137Cs+ and 90Sr2+ ion exchangers is achieved through heteroatom-bridged integration of polyoxovanadate clusters, whose soft Lewis basic nature and large size promote the selective capture of cesium/strontium radionuclides. The radiolytically stable Na6P4V10O34·19H2O (VPO-1) features an interlinkage of {NaV10O26} clusters and phosphorus bridges, forming nanoscale voids with hydration-lubricated sodium ions. This structure endows VPO-1 with remarkable exchange kinetics (k2Cs = 3.774 g mg−1 min−1; k2Sr = 1.376 g mg−1 min−1), equilibrium removal (R > 99.3% within 5–10 min), and maximum capacities (qmCs = 300.32 mg g−1; qmSr = 113.00 mg g−1). The exchange mechanism is illuminated through single-crystal XRD by revealing cluster-vacancy pathways and ionic-radius-dependent adsorption sites. VPO-1 exhibits stability across pH = 3–12, with exceptional KdCs and KdSr values above 105 mL g−1, and high selectivity for Cs+ and Sr2+ over various competing ions. These properties enable excellent column filtration performance (R = 99%–100%) for mixed Cs+ and Sr2+ during a 3000 mL test. Deep cleaning of these ions is also possible via suction filtration using an ultra-thin VPO-1/PTFE membrane, with high exchange activity (R = 98.8%–99.9%) retained after simple regeneration with 2 m NaCl, offering significant potential for nuclear wastewater treatment applications.