The design and synthesis of a bifunctional catalyst to tackle environmental pollution caused by 2-chloroethyl ethyl sulfide (CEES) and phenolic compounds is meaningful. In this study, a new three-dimensional (3D) polyoxovanadate (POV)-based metal–organic framework, [Co(L)(V₄O₁₂)_0.5(H₂O)]·2H₂O (1; L = N,N’-bis(3-methylpyridin-3-yl)-2,6-naphthalenediamide), was synthesized under hydrothermal conditions. 1 was characterized using single-crystal X-ray diffraction analysis, infrared spectroscopy, and powder X-ray diffraction. Structural analysis shows that the [V₄O₁₂]^4– clusters and pairs of Co²⁺ cations are alternately connected to form a one-dimensional inorganic chain, eventually generating a 3D (4,4)-connected framework through the expansion of L, which exhibits a two fold interpenetration array. As a bifunctional catalyst, 1 exhibits satisfactory catalytic properties for the selective oxidation of 2-chloroethyl ethyl sulfide to the corresponding sulfoxide, with an effective conversion of > 99% and selectivity of 97%. Furthermore, 1 exhibits excellent photocatalytic degradation activity toward phenol, 2-chlorophenol, and m-cresol under visible light. The degradation efficiencies were above 92.6% for 140 min. The photocatalytic reaction kinetics, mechanisms of photodegradation, and recycling capability of phenol were also investigated in detail.