Highlights:　We　developed　an　efficient　and　extensible　strategy　to　produce　the　single-phase　ternary　NbSSe　nanohybrids　with　defect-enrich　microstructure.The　anionic-Se　doping　play　a　key　role　in　effectively　modulating　the　electronic　structure　and　surface　chemistry　of　NbS2　phase,　including　the　increased　interlayers　distance　(0.65　nm),　the　enhanced　intrinsic　electrical　conductivity　(3.23　×　103　S　m-1)　and　extra　electroactive　defect　sites.The　NbSSe/NC　composite　as　anode　exhibits　rapid　Na+　diffusion　kinetics　and　increased　capacitance　behavior　for　Na+　storage,　resulting　in　high　reversible　capacity　and　excellent　cycling　stability.　Abstract:　Sodium-based　dual-ion　batteries　(SDIBs)　have　gained　tremendous　attention　due　to　their　virtues　of　high　operating　voltage　and　low　cost,　yet　it　remains　a　tough　challenge　for　the　development　of　ideal　anode　material　of　SDIBs　featuring　with　high　kinetics　and　long　durability.　Herein,　we　report　the　design　and　fabrication　of　N-doped　carbon　film-modified　niobium　sulfur–selenium　(NbSSe/NC)　nanosheets　architecture,　which　holds　favorable　merits　for　Na+　storage　of　enlarged　interlayer　space,　improved　electrical　conductivity,　as　well　as　enhanced　reaction　reversibility,　endowing　it　with　high　capacity,　high-rate　capability　and　high　cycling　stability.　The　combined　electrochemical　studies　with　density　functional　theory　calculation　reveal　that　the　enriched　defects　in　such　nanosheets　architecture　can　benefit　for　facilitating　charge　transfer　and　Na+　adsorption　to　speed　the　electrochemical　kinetics.　The　NbSSe/NC　composites　are　studied　as　the　anode　of　a　full　SDIBs　by　pairing　the　expanded　graphite　as　cathode,　which　shows　an　impressively　cyclic　durability　with　negligible　capacity　attenuation　over　1000　cycles　at　0.5　A　g−1,　as　well　as　an　outstanding　energy　density　of　230.6　Wh　kg−1　based　on　the　total　mass　of　anode　and　cathode.[Figure　not　available:　see　fulltext.]　©　2023,　The　Author(s).