Defect-mediated　engineering　has　been　proven　as　a　novel　and　effective　strategy　to　integrate　two　individual　materials　into　a　nanocomposite　to　boost　the　performance.　In　the　present　work,　nanocomposite　of　partially-unzipped　stacked-cup　carbon　nanofibers　(PUSCNFs)　decorated　with　platinum　nanoparticles　(Pt NPs)　have　been　successfully　synthesized　through　the　defect-mediated　formation　method.　Owing　to　the　introduction　of　abundant　structural　defects　during　the　chemical　oxidation　process,　Pt　NPs　with　an　average　diameter　of　2–3 nm　were　uniformly　anchored　on　the　PUSCNFs　without　any　surfactant　involved.　As　comparison,　the　Pt　NPs　grown　on　the　stacked-cup　carbon　nanofibers　(SCNFs)　possessed　markedly　larger　nanoparticle　size　and　trended　to　aggregate.　The　electrochemical　properties　of　the　nanocomposite-modified　electrodes　for　biosensing　were　examined.　Our　results　showed　the　Pt-PUSCNFs　nanocomposite　possessed　optimal　electrocatalytic　activities　and　biosensing　performance　for　detection　of　biomolecules,　which　could　be　attributed　to　a　synergistic　effect　between　the　PUSCNFs　and　Pt　NPs　on　electron　transport　and　catalytic　properties.　We　anticipate　that　the　PUSCNFs　may　be　a　potential　support　material　for　construction　of　nanocomposites　with　good　performance.　©　2017