The development of materials for the remediation and monitoring of water environments remains a significant challenge in the field of environment and materials science. In this study, a nickel-based coordination polymer, [Ni(L)(H₂O)₃]_n·nH₂O (1), was synthesized employing 4,4′-(1H,1′H-[2,2′-biimidazole]-1,1′-diyl)dibenzoic acid (H₂L). Single-crystal X-ray diffraction analysis showed that L²⁻ ligands connect Ni²⁺ ions into 1D Z-shaped chains via two coordination modes. The chains are further assembled into a 3D supramolecular structure through hydrogen bonding interactions. The photocatalytic test showed that complex 1 could effectively degrade the organic dye methylene blue (MB). Under the conditions of catalyst dosage 5 mg, MB initial concentration 20 ppm and pH 7, the degradation efficiency reached 87.7% within 180 min. In addition, complex 1 can be used for the electrochemical detection of norfloxacin (NOR) by differential pulse voltammetry (DPV), exhibiting a linear response in the concentration range of 2–197 μM and the detection limit (LOD) of 1.74 μM. These results demonstrate that complex 1 has bifunctional properties of photocatalytic degradation of organic dyes and electrochemical sensing of antibiotic NOR, making it a promising candidate material for the synergistic treatment of complex pollutants.