Herein, the defects and surface oxygen functionalities of multi-walled carbon nanotubes (MWCNTs) derived from a solid state reaction are demonstrated to be effective in the activation of peroxymonosulfate (PMS) for organic pollutant degradation. The catalytic activity of defective, oxygen-functionalized CNTs (dCNTs) is much better than bare CNTs, which stems from many active sites on the CNT surface, including structural defects and carbonyl functional groups, and excellent electrical conductivity. Furthermore, the effect of several operational factors and water conditions on the degradation rate of the targeted pollutant and material stability are comprehensively evaluated for the practical application of the dCNT/PMS-coupled process. The underlying catalytic mechanism in dCNTs is expected to take place via nonradical pathway and radical-induced oxidation where surface-bound radicals play a more dominant role than free radicals. The defect and oxygen functional group tuning strategy provides an effective methodology for the development of advanced carbon catalysts in Fenton-like reactions.