In the present study, the cyanobacterial char (ACC) prepared from Chaohu cyanobacteria was used as a nanoscale carrier for zero-valent iron (NZVI) to synthesize a highly efficient activation material designated as cyanobacterial char-supported nanoscale zero-valent iron ([email protected]), which was subsequently used for activating peroxymonosulfate (PMS) to degrade the orange II (OII) dye. The XRD and XPS results revealed that NZVI was anchored onto the ACC through coordination bonding, thereby forming a stable structure. The SEM and TEM observations revealed that the NZVI was embedded in the sheet structure of the ACC. The [email protected] had a larger specific surface area (42.249 m2/g), and also magnetism, due to which its components could be separated through an externally applied magnetic field. Using this [email protected]/PMS system, the rate of degradation of OII (100 mg/L) reached 98.32% within 14 min. The OII degradation reaction using the [email protected]/PMS system followed first-order kinetics. The activation energy of this degradation reaction was 17.34 kJ/(mol·K). Quenching and EPR experiments revealed that both SO4·– and ·OH were produced in this reaction, with SO4·- playing the major role in the reaction. The theoretical calculations revealed that SO4·- attacked the 12 (N) of OII, which destroyed and degraded the structure of OII. The presence of halogen ions in the actual dye-containing wastewater samples inhibited the OII degradation by the [email protected] system to different degrees, and the inhibition effect followed the order: I- > Br- > Cl-.