In　the　development　of　nanoscale　oxygen　electrodes　of　high-temperature　solid　oxide　cells　(SOCs),　the　interface　formed　between　the　nanoelectrode　particles　and　the　electrolyte　or　electrolyte　scaffolds　is　the　most　critical.　In　this　work,　a　new　synthesis　technique　for　the　fabrication　of　nanostructured　electrodes　via　in　situ　electrochemical　polarization　treatment　is　reported.　The　lanthanum　strontium　cobalt　ferrite　(LSCF)　precursor　solution　is　infiltrated　into　a　gadolinia-doped　ceria　(GDC)　scaffold　presintered　on　a　yttria-stabilized　zirconia　(YSZ)　electrolyte,　followed　by　in　situ　polarization　current　treatment　at　SOC　operation　temperatures.　Electrode　ohmic　and　polarization　resistances　decrease　with　an　increase　in　the　polarization　current　treatment.　Detailed　microstructure　analysis　indicates　the　formation　of　a　convex-shaped　interface　between　the　LSCF　nanoparticles　(NPs)　and　the　GDC　scaffold,　very　different　from　the　flat　contact　between　LSCF　and　GDC　observed　after　heating　at　800　°C　with　no　polarization　current　treatment.　The　embedded　LSCF　NPs　on　the　GDC　scaffold　contribute　to　the　superior　stability　under　both　fuel　cell　and　electrolysis　operation　conditions　at　750　°C　and　a　high　peak　power　density　of　1.58　W　cm-2　at　750　°C.　This　work　highlights　a　novel　and　facile　route　to　in　situ　construct　a　stable　and　high-performing　nanostructured　electrode　for　SOCs.　©　2024　American　Chemical　Society.