Atomically　precise　low-nuclearity　(n＜10)　silver　nanoclusters　(AgNCs)　have　garnered　significant　interest　due　to　their　size-dependent　optical　properties　and　diverse　applications.　However,　their　synthesis　has　remained　challenging,　primarily　due　to　their　inherent　instability.　The　present　study　introduces　a　new　feasible　approach　for　clustering　silver　ions　utilizing　highly　negative　and　redox-inert　polyoxoniobates　(PONbs)　as　all-inorganic　ligands.　This　strategy　not　only　enables　the　creation　of　novel　Ag-PONb　composite　nanoclusters　but　also　facilitates　the　synthesis　of　stable　low-nuclearity　AgNCs.　Using　this　method,　we　have　successfully　synthesized　a　small　octanuclear　rhombic　[Ag-8](6+)　AgNC　stabilized　by　six　highly　negative　[LiNb27O75](14-)　polyoxoanions.　This　marks　the　first　PONb-protected　superatomic　AgNC,　designated　as　{Ag-8@(LiNb27O75)(6)}　(Ag-8@Nb-162),　with　an　aesthetically　spherical　core-shell　structure.　The　crystalline　Ag-8@Nb-162　is　stable　under　ambient　conditions,　What＇s　more,　it　is　water-soluble　and　able　to　maintain　its　molecular　cluster　structure　intact　in　water.　Further,　the　stable　small　[Ag-8](6+)　AgNC　has　interesting　temperature-　and　pH-dependent　reversible　fluorescence　response,　based　on　which　a　multiple　optical　encryption　mode　for　anti-counterfeit　technology　was　demonstrated.　This　work　offers　a　promising　avenue　for　the　synthesis　of　fascinating　and　stable　PONb-protected　AgNCs　and　sheds　light　on　the　development　of　new-type　optical　functional　materials.