Two new cadmium(II) coordination compounds, [Cd4(SBTC)2(2,2′‐bpy)6(H2O)4](2,2′‐bpy) (1) (2,2′‐bpy = 2,2′‐bipyridyl) and {[K2Cd(SBTC)(H2O)4](H2O)2}n (2), were synthesized using a novel ligand of 5‐sulfonyl‐1,2,4‐bezenetricarboxylic acid (H4‐SBTC) featuring three carboxylate groups and one sulfonate group stationed on a phenyl central motif. Compound 1 is a discrete tetranuclear [Cd4(SBTC)2(2,2′‐bpy)6(H2O)4] structure with a solvated 2,2′‐bpy molecule, wherein the four cadmium ions are bridged by two μ3‐SBTC4– ligands. The discrete tetranuclear [Cd4(SBTC)2(2,2′‐bpy)6(H2O)4] motif is extended into a three‐dimensional (3D) supramolecular framework through hydrogen bonds and π–π interactions. In compound 2 the cadmium ions and potassium ions are interconnected by the SBTC4– ligands and bridging water molecules to give a complex 3D structure. The 3D structure is constructed by a rare 3D inorganic cadmium‐potassium‐oxide framework, in which the cadmium and potassium ions are bridged by the sulfonate groups and bridging water molecules. In the solid state, compounds 1 and 2 exhibit photoluminescence with emission maximum at 380 and 445 nm, respectively.