The synthesis of a trinuclear Co(II)‐based coordination polymer (CP), [Co3(HL)2(H2O)6·2.2H2O]n (1), was achieved via a solvothermal method involving CoCl2·6H2O and 3‐(2,4‐dicarboxylphenyl)‐2,6‐dicarboxylpyridine (H3L). The photocatalytic efficiency of the complex was evaluated for the degradation of various antibiotics ornidazole (ODZ), nitrofurantoin (NFT), dinitroaniline (DNZ), and tinidazole (TDZ) in wastewater. Notably, NFT exhibited a remarkable 91.5% degradation within 20 min under optimal conditions. The catalytic performance was influenced by the amount of photocatalyst, NFT concentration, and solution pH, with optimal conditions identified at 6‐mg catalyst dose, 30 mg/L NFT concentration, and pH 7. Trapping experiments highlighted the roles of superoxide and hydroxyl radicals as primary active species in the photocatalytic process. Furthermore, the magnetic behavior is also discussed in detail.