The recalcitrance and biological toxicity of phenolic pollutants pose a serious threat to the safety of aquatic environments, and developing efficient and stable catalytic degradation technologies is a key research focus in the current environmental field. In this study, a composite material (MSN) of NH₂-MIL-101(Fe) modified by MoSe₂ nanosheets was constructed via a one-step composite strategy, aiming to address the bottlenecks of low Fe³⁺/Fe²⁺ cycling efficiency and iron ion leaching in traditional Fe-based MOFs when activating peroxymonosulfate (PMS). Characterization results showed that MoSe₂ nanosheets were uniformly dispersed on the surface of NH₂-MIL-101(Fe), and strong electronic interactions existed between them, which significantly optimized the electronic environment of active sites. MSN-3 exhibited excellent performance in activating PMS for phenol degradation: the degradation rate reached 90% within 30 min, with a k = 0.073 min⁻¹, which was much higher than that of other systems. It also showed good structural stability and cyclic regeneration ability. Mechanistic studies confirmed that the core active species in the MSN-3/PMS system are ¹O₂, •SO₄⁻ and •OH. The two-dimensional layered structure of MoSe₂ can serve as an efficient electron transport bridge to promote Fe³⁺/Fe²⁺ cycling; amino modification further optimizes the electron density of Fe active centers. The two synergistically construct a dual redox cycle of Fe³⁺/Fe²⁺ and Mo⁴⁺/Mo⁶⁺, significantly enhancing PMS activation efficiency and ¹O₂ production. This study provides a new strategy for designing Fe-MOFs-based PMS activation catalysts and also offers technical support for the practical treatment of recalcitrant organic pollutants in water.