Supercapacitors　have　grabbed　a　lot　of　limelight　and　have　been　under　extensive　scrutiny　by　researchers　for　their　advantages　over　competitors,　such　as　high　power　density,　long-term　cycle　life,　accelerated　charging　and　discharging,　security,　and　environmental　sustainability.　Herein,　the　hydrothermal　combination　with　coprecipitation　approach　is　effectively　used　to　create　Bi2Fe4O9　particles　with　various　morphologies　through　controlling　the　concentrations　of　NaOH,　and　they　show　significant　discrepancies　in　their　electrochemical　characteristics.　The　chamfered　square　plate-like　Bi2Fe4O9　particles　(Bi2Fe4O9-3)　obtained　at　a　NaOH　concentration　of　12　M　demonstrate　pseudocapacitive　or　battery-like　behavior　in　a　three-electrode　system　and　exhibited　optimum　electrochemical　properties,　displaying　a　mass-specific　capacitance　of　443.8　F　g-1　at　1.0　A　g-1.　In　terms　of　electrochemical　characteristics　and　long-term　cycling　stability,　the　Bi2Fe4O9-3　sample　also　displays　an　extraordinary　Coulombic　efficiency　of　98.87　%　and　capacitance　retention　rate　of　142　%　after　completing　5000　cycles　of　galvanostatic　charge-discharge.　Moreover,　the　self-assembled　asymmetric　supercapacitor　device　has　an　energy　density　of　21.11　Wh　kg-1　at　a　power　density　of　424.26　W　kg-1.　Bi2Fe4O9-3　has　been　meticulously　fabricated　as　an　innovative　and　inimitable　electrode　material　that　manifests　brilliant　electrochemical　properties,　rendering　it　prospective　for　progressive　application　in　the　supercapacitors　realm　by　researchers　in　the　future.