Display omitted •Fast preparation of graphene nanosheets by one-pot radiolytic reduction of GO.•One-pot synthesis of graphene nanosheets supported Au-Pt-Pd nanoparticles.•Radiolysis enables to engineer highly active Metal/rGO nanocomposites.•Ternary Au50Pt25Pd25/rGO electrocatalyst is 5-fold higher effective than Pt/rGO.•Selective glucose oxidation reaction in a 2-electron process leads to gluconate. We report a novel “one-pot”, convenient and efficient method based on radiolysis to synthesize gold-based nanoparticles finely dispersed on reduced graphene oxide (rGO) nanosheets obtained from reductive transformation of graphene oxide (GO). Extensive characterizations of the metal/rGO nanocomposites were performed and revealed that the optimized bimetallic Au90Pd10 and trimetallic Au50Pd25Pt25 materials were mostly nano-alloyed. Not only the multimetallic catalysts demonstrate high electrocatalytic performances towards glucose in alkaline medium, but they also surpass the majority of the reported noble metals based nanocatalysts. The spectroelectrochemical investigations have highlighted a 2-electron reaction process leading to gluconate, a high added-value chemical used in various industries. Definitely, the strategies developed herein pave new rational pathways for the design of effective anode catalysts for glucose-based electrochemical energy converters and the scalability in the catalyst composition opens up new avenues in the efficient application of graphene-based nanocomposites as promising electrode materials in the electrocatalysis of carbohydrates.