<p>Photocatalytic technology is a significant approach to addressing environmental pollution, highlighting the strategic importance of developing novel, high efficiency photocatalysts. This study prepares hierarchical PbBiO₂Br/Mo₂CTx composites via in situ hydrothermal growth of PbBiO₂Br nanoflowers on MXene Mo₂CTx nanosheets. Morphological and structural characterization confirms that PbBiO₂Br nanoflowers encapsulate Mo₂CT_x nanosheets, forming a three-dimensional porous architecture. Photocatalytic degradation tests show the composite exhibits superior activity to pure PbBiO₂Br for ciprofloxacin degradation: the 5 wt% Mo₂CTx-loaded sample shows a degradation efficiency 4.3 times that of pristine PbBiO₂Br and 9.4 times that of bare Mo₂CTx, with a kinetic constant approximately 11.02 times that of pure PbBiO₂Br and 25.15 times that of pure Mo₂CTx. Steady-state/transient PL, EPR, and photoelectrochemical measurements demonstrate that the composite’s photogenerated charge separation and migration efficiency are markedly enhanced. This is attributed to Mo₂CTx acting as an electron reservoir to suppress charge recombination, while the unique hierarchical structure promotes interfacial charge transfer and exposes more active sites. A novel photocatalytic mechanism and antibiotic degradation pathway are proposed, providing important references for the development of MXene-based composite photocatalysts and their application in antibiotic degradation.</p><?pagebreak??> Graphical Abstract <p></p> <p>The figure intuitively demonstrates the reaction mechanism and the superior photocatalytic performance of 5Mo</p>