Polybrominated diphenyl ethers (PBDEs) are a family of important organic pollutants, and methods for their complete debromination are urgently needed. It is known that highly-brominated PBDEs are easily photo-catalytically reduced to lower-brominated congeners, and the lower-brominated congeners are relatively susceptible to photocatalytic oxidation but not to further reduction. The present work developed a one-pot photocatalytic consecutive reduction and oxidation method (O-CRO) for the complete debromination of 2,2', 4,4'-tetrabromodiphenyl ether (BDE47). It was observed that BDE47 was resistant to photocatalytic reduction on TiO2 but underwent a slow oxidation in aerobic aqueous solutions (rate constant k=0.065 h(-1)). The use of a reduced graphene oxide and TiO2 (RGO/TiO2) composite only slightly improved the photocatalytic oxidation of BDE47 in air-H2O systems (k=0.12 h(-1)), but achieved a rapid photocatalytic reduction of BDE47 (k=0.81 h(-1)) in anoxic ACN-H2O systems; however, the debromination was only 25.0% even after 14 h because the reduction intermediates (i.e., tri-BDEs) were minimally reduced. To conduct the O-CRO process, we developed an anoxic RGO/TiO2-H2O system containing a small amount of methanol. This system yielded the complete debromination and mineralization of BDE47 within 14 h. The mechanism for the debromination and mineralization of BDE47 was clarified. This method overcame the drawbacks of the separated two-step reduction and oxidation method and will find promising applications for the degradation of halogenated organic pollutants.