Hexagonal boron nitride (BN) nanomaterials that possess an extensive specific surface area, negatively charged properties, high thermal conductivity, and excellent chemical characteristics, have significant advantages for water purification and energy storage. They are typically considered as potential catalysts due to their wide tunable bandgap. Here, carbon nitride (CN) modified BN (CMBN), which facilitated the formation of new C-N-B bonds, was successfully synthesized using a facile hydrothermal-calcination synthesis strategy. Such highly active bonds made the photocatalyst responsive to a wider range of wavelengths (e.g., ultraviolet to visible blue light), while significantly enhancing photocatalytic activity toward the degradation of enrofloxacin (ENFX). A 3-CMBN sample exhibited 39.3 times, and 2.4 times, higher photocatalytic properties than that of pristine BN and CN, respectively. The remarkable response of 5, 5-dimethyl-l-pyrrolidone-N-oxyl (DMPDX) was investigated through electron spin resonance spectroscopy (EPR) with 3-CMBN, which indicated higher oxidability than BN and CN under blue LED irradiation. Reactive species scavenging experiments revealed that the photodegradation of ENFX was dominated by electron holes and O-2 center dot(-). Moreover, the byproducts of ENFX were detected by HPLC-Q-TOF and GC-MS, probable pathways toward these byproducts were deduced, and repeated tests confirmed good stability. These results provided a new strategy to guide the enhanced design of advanced photocatalysts with active chemical bonding species, which can be applied to environmental remediation.