The　reduction　of　CO2　with　visible　light　is　a　highly　sustainable　method　for　producing　valuable　chemicals.　The　function-led　design　of　organic　conjugated　semiconductors　with　more　chemical　variety　than　that　of　inorganic　semiconductors　has　emerged　as　a　method　for　achieving　carbon　photofixation　chemistry.　Here,　we　report　the　molecular　engineering　of　triazine-based　conjugated　microporous　polymers　to　capture,　activate　and　reduce　CO2　to　CO　with　visible　light.　The　optical　band　gap　of　the　CMPs　is　engineered　by　varying　the　organic　electron-withdrawing　(benzothiadiazole)　and　electron-donating　units　(thiophene)　on　the　skeleton　of　the　triazine　rings　while　creating　organic　donor–acceptor　junctions　to　promote　the　charge　separation.　This　engineering　also　provides　control　of　the　texture,　surface　functionality　and　redox　potentials　of　CMPs　for　achieving　the　light-induced　conversion　of　CO2　to　CO　ambient　conditions.　©　2018　Wiley-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim