The　construction　of　strong　metal-support　interactions　(SMSI)　is　an　effective　strategy　to　enhance　and　control　heterogeneous　catalysts.　However,　conventional　methods　require　pre-synthesized　metal-loaded　catalysts,　followed　by　SMSI　formation　via　high-temperature　treatment　under　oxidative/reductive　atmospheres,　adsorbate-mediated　treatment,　and　photo-treatment,　adding　complexity　to　catalyst　synthesis　and　hindering　continuous　interfacial　tuning.　In　this　work,　a　＂photobreeding＂　method　is　employed　to　treat　Zn0.8Cd0.2S,　leveraging　the　UV-induced　photochromic　reaction　of　ZnS　to　generate　metallic　Zn　at　room　temperature,　while　CdS　remains　inert.　Zn0.8Cd0.2S-derived　CdS　directly　encapsulates　the　generated　Zn,　enabling　direct　synthesis　of　SMSI　catalysts　without　additional　treatments.　Furthermore,　the　interfacial　properties　can　be　continuously　tuned　by　adjusting　the　photobreeding　duration.　The　catalytic　performance　of　SMSI　catalysts　synthesized　via　photobreeding　exhibits　a　3.1-fold　enhancement　over　the　initial　catalysts.　To　further　boost　performance,　viologen,　an　electron　mediator,　is　introduced　to　form　a　surface　charge　transfer　complex.　The　resulting　ZCS-SMSI-120/PV　exhibits　a　hydrogen　evolution　rate　of　48.7　mmolg-1h-1　without　the　use　of　noble　metals,　representing　one　of　the　highest　values　reported　to　date.　This　direct　SMSI　synthesis　approach　holds　promise　for　applications　in　H2　production,　CO2　reduction,　biomass　conversion,　organic　synthesis,　and　so　on.