N-cadherin　serves　as　an　important　oncobiomarker　of　epithelial-to-mesenchymal　transition　(EMT)　progression,　which　identifies　invasion　and　metastasis　of　malignant　tumor　cells.　Although　many　efforts　have　been　devoted　to　quantitative　detection　of　N-cadherin,　efforts　to　analyzing　the　protein　of　interest　at　intact　cellular　levels　are　scarce.　Herein,　a　metal　cluster-based　electrochemical　biosensing　system　is　developed　to　determine　the　expressing　levels　of　N-cadherin　during　the　EMT　process　of　tumor　cells.　To　be　specific,　a　peptide　with　a　unique　sequence　and　function　is　designed　as　a　reductant　and　an　anchor　to　synthesize　metal　clusters　in　a　precise　manner.　Consequently,　peptide-modified　metal　clusters　possess　N-cadherin-targeting,　photoluminescence,　and　electrocatalytic　properties.　Especially,　the　redox-active　metal　clusters　function　as　both　an　electron-transfer　mediator　and　an　electronic　conductor　for　enhanced　electrochemical　sensing.　These　favorable　features　enable　them　as　a　rapid,　sensitive,　and　reliable　whole-cell　biosensor,　which　integrates　the　fluorescence　and　electrochemical　signals.　This　cytosensor　can　accurately　quantify　the　expression　levels　of　N-cadherin　on　at　least　5000　tumor　cells.　Further,　the　current　signals　of　model　cancer　cells　gradually　increase　with　EMT　progression,　indicating　tumor　cell-type　evolution.　Our　study　represents　the　advanced　bioprobe　and　analytical　methods　for　accurate　quantitation　of　a　biomarker　to　identify　tumor　progression.