In　this　study,　graphene　nanofibers　(GNF),　which　are　a　superior　support　material,　are　successfully　synthesized　via　the　dendritic　unzipping　of　stacked-cup　carbon　nanofibers　(SCNF).　Ultrasmall　Pd　nanoparticles　are　uniformly　dispersed　on　the　GNF　(Pd/GNF)　via　chemical　reduction　under　mild　conditions　without　any　surfactant　involved.　The　components　and　structure　of　Pd/GNF　are　evaluated　via　scanning　electron　microscopy　(SEM),　transmission　electron　microscopy　(TEM),　powder　X-ray　diffraction　(XRD),　Raman　spectra　and　X-ray　photoelectron　spectroscopy　(XPS).　The　characterization　results　indicate　that　the　Pd　nanoparticles　have　a　uniform　size　of　3-6　nm　without　significant　aggregation　and　the　overall　Pd　content　is　about　11.2　wt%　in　the　Pd/GNF　composite.　Moreover,　a　modified　electrochemical　sensor　based　on　the　Pd/GNF　composite　is　successfully　fabricated.　In　the　two　investigated　redox　probes　(IrCl6　2−　and　[Fe(CN)6]3−),　Pd/GNF　shows　a　superior　electrochemical　response　compared　to　the　Pd　nanoparticles　loaded　on　SCNF　and　bare　glass　carbon　electrode.　For　the　detection　of　small　biomolecules,　Pd/GNF　could　individually　or　simultaneously　detect　ascorbic　acid　(AA),　dopamine　(DA)　and　uric　acid　(UA)　through　differential　pulse　voltammetry.　The　linear　concentration　ranges　of　UA,　DA　and　AA　are　0.1-1200　μM,　1-180　μM　and　0.1-6000　μM,　respectively.　©　The　Royal　Society　of　Chemistry.