The　development　of　efficient　and　sustainable　methods　to　obtain　spirocyclic　compounds　is　of　significance　as　these　structures　are　widely　found　in　pharmaceuticals　and　agrochemicals.　Herein,　we　disclose　an　electrochemical　dearomative　spirocyclization　of　N-acyl　sulfonamides　in　a　continuous-flow　cell.　The　reaction　is　simple　and　efficient　without　external　catalysts　or　supporting　electrolytes　and　could　be　applied　in　a　decagram-scale　synthesis.