A facile one-pot method was used to synthesize Pt/Cu₂O/GNs and Pd/Cu₂O/GNs composites. Pt or Pd nanoparticles are deposited onto graphene sheets (GNs) and Cu₂O via synchronous reduction of K₂PtCl₄ (K₂PdCl₄), Cu(OH)₂ and graphene oxide (GO) with glucose as a reducing agent under microwave irradiation. The formation of Cu₂O promotes the nucleation of Pt(0) or Pd(0) particles and favors more complete reduction of PtCl₄²⁻ or PdCl₄²⁻. Catalytic properties of as-prepared composites for methanol oxidation reaction (MOR) were evaluated by cyclic voltammetry (CV), chronoamperometry, CO_ads stripping voltammetry and electrochemical impedance spectrum (EIS). Electrochemical experiments showed that Pt/Cu₂O/GNs and Pd/Cu₂O/GNs had much higher catalytic activity and stability for MOR and better resistance to CO poisoning compared with the commercially available Johnson Matthey 20% Pt/C catalyst (Pt/C-JM) and Sigma-Aldrich 20% Pd/C catalyst (Pd/C-SA). Especially under the UV irradiation, the total peak current density and catalytic stability of Pt/Cu₂O/GNs and Pd/Cu₂O/GNs drastically increase, which may result from the synergistic effect between the electro-catalytic and photo-catalytic properties. In brief, the cooperation among Pt (Pd), Cu₂O and GNs promotes remarkably the catalytic performance for MOR on Pt/Cu₂O/GNs and Pd/Cu₂O/GNs either without light or with UV irradiation.