In　this　research　article,　a　novel　and　simple　label-free　electrochemiluminescence　(ECL)　immunosensor　using　cerium　stannite　(Ce2Sn2O7)　nanocubes　as　brand-new　ECL　emitters　has　been　suggested　for　the　first　time.　Ce2Sn2O7　nanocubes　prepared　by　a　simple　hydrothermal　method　displayed　bright　ECL　emission,　promising　biocompatibility,　low　noxiousness,　and　perfect　stability.　On　comparison　of　ECL　and　photoluminescence　(PL)　spectra,　a　surface-state　mechanism　was　proposed　to　be　involved　in　the　ECL　emission.　After　aminofunctionalization　with　3-aminopropyltriethoxysilane　(APTES),　Ce2Sn2O7　could　be　decorated　with　gold　nanoparticles　through　Au-NH2　covalent　linkage,　which　yielded　Au@Ce2Sn2O7　nanocomposites　and　further　enhanced　the　ECL　emission.　To　confirm　the　proposed　immunosensor　feasibility,　carcinoembryonic　antigen　(CEA)　was　employed　as　an　exemplary　analyte.　Based　on　the　abovementioned　points,　our　fabricated　immunosensor　improved　the　ECL　performance　to　CEA　concentrations　in　a　linear　range　of　0.001-70　ng/mL　with　a　low　limit　of　detection　of　0.53　pg/mL　(S/N　=　3).　With　outstanding　stability,　reproducibility,　and　specificity,　this　method　is　expected　to　be　an　innovative　one　for　sensitive　analyses　of　CEA　and　other　biomarkers　in　real　samples.　©　2021　American　Chemical　Society.