In the present work, platinum-nickel (PtNi) bimetallic nanoparticles with a uniform diameter of 40 nm were anchored onto a three-dimensional graphene (3DGN) by using the method of electrodeposition. The resulting PtNi/3DGN composites were developed toward highly active catalysts for methanol oxidation. Experimental results revealed that the PtNi/3DGN composites exhibited improved electrocatalytic capacity (the forward anodic peak current density of 822.1 mA/mgPt in methanol oxidation when compared with Pt alone (251.2 mA/mgPt) and Pt/3DGN (416.9 mA/mgPt), and indicated the high tolerance to carbon monoxide generated in the process of methanol oxidation.