This　work　demonstrates　that　the　photoelectric　response　of　defect-engineered　TiO2-x　modified　with　Au　nanoparticles　can　be　modulated　by　oxygen　vacancy　concentration　and　excitation　wavelength.　When　strongly　plasmonic　Au　nanoparticles　are　anchored　to　defect-engineered　TiO2-x　by　DNA　hybridization,　several　times　plasmonic　enhancement　of　photocurrent　occurs　under　585　nm　excitation,　and　it　is　employed　as　a　novel　signaling　mode　for　developing　an　improved　photoelectrochemical　sensing　platform.　This　signaling　mode　combined　with　exonuclease　III-assisted　target　recycling　amplification　exhibits　excellent　analytical　performance,　which　provides　a　novel　photoelectrochemical　detection　protocol.　©　2018　American　Chemical　Society.