Green　phosphorene　(GP),　a　novel　two-dimensional　(2D)　allotrope　of　phosphorus,　has　emerged　as　a　promising　photocatalyst　for　overall　water　splitting　due　to　its　layer-tunable　band　structure　and　exceptional　charge　carrier　mobility.　However,　its　practical　application　is　severely　limited　by　rapid　electron-hole　recombination,　insufficient　visible-light　absorption,　and　catalytically　inert　surfaces.　To　address　these　challenges,　we　propose　a　synergistic　defect　and　doping　engineering　strategy,　systematically　investigated　through　density　functional　theory　(DFT)　simulations.　By　introducing　Stone-Wales　(SW)　defects　and　subsequent　Bi　doping　(termed　SW-1-GP@Bi),　the　modified　GP　exhibited　remarkable　photocatalytic　enhancements,　including　an　extended　visible-light　absorption　with　a　redshifted　spectrum,　a　near-optimal　hydrogen　evolution　reaction　(HER)　Gibbs　free　energy　(ΔGH=0.05eV),　and　a　significantly　reduced　oxygen　evolution　reaction　(OER)　overpotential　of　0.51　V　at　pH　=　9　under　illumination.　The　enhanced　performance　originates　from　two　key　mechanisms:　(1)　SW　defects　spatially　separate　electron-hole　pairs,　suppressing　recombination,　and　(2)　Bi　doping　tailors　the　surface　electronic　structure,　optimizing　hydrogen　and　oxygen　intermediates　adsorption.　Our　work　demonstrates　that　defect-dopant　synergy　can　effectively　activate　inert　basal　planes　of　GP,　achieving　balanced　HER/OER　activities　for　standalone　water　splitting.　This　strategy　provides　a　universal　framework　for　designing　high　efficiency　2D　photocatalysts　toward　scalable　solar　hydrogen　production.　©　2025　Elsevier　B.V.