A Sb/graphene nanohybrid has been synthesized by a facile in situ solvothermal route using SbCl3 and graphite oxide as the precursors and NaBH4 as the reducing agent. Microstructural observation reveals the sheet-like nanostructure consisting of Sb nanocrystals (50–100 nm) attached on few-layer graphene nanosheets. The in situ introduced graphene uniformly disperses the Sb nanocrystals, while the attached Sb nanocrystals hinder the restacking of the graphene nanosheets. The introduction of graphene remarkably improves the electrochemical Li and Na-storage properties of Sb due to the combined buffering, confining and conducting effects of graphene. The underlying mechanism for the enhanced Li and Na-storage properties has been investigated by chemical diffusion coefficient and electrochemical impedance spectroscopy measurement.