A flexible　photoelectrochemical　(PEC)　biosensor　is proposed　for　the　sensitive　detection　of　ochratoxin　A　(OTA)　based　on　glucose　oxidase　(GOx)-encapsulated　target-responsive　hydrogel,　using　Fenton　reaction-mediated　in　situ　formation　of　polyaniline　(PANI)　as　signal　amplified　strategy.　The　target-responsive　DNA　hydrogels　with　high　loading　capacity　can　carry　a　large　amount　of　GOx,　which　not　only　avoids　laborious　labeling　process　but　also　enhances　the　analytical　performance.　Upon　introduction　of　target　molecules,　the　hydrogel　can　be　opened,　and　multiple　GOx　was　released,　thus　producing　lots　of　H2O2　via　catalytic　reduction　of　glucose.　As　a　component　of　the　Fenton　reagent,　H2O2　can　react　with　the　Fe2+　on　the　graphene　oxidase-PAMAM-Fe2+　(GO-PAMAM-Fe2+)　to　generate　Fe3+　and　·OH.　This　in　turn　can　oxidize　aniline　and　generate　polyaniline　(PANI),　resulting　in　the　enhancement　of　the　photocurrent　signal　of　GO-MoS2-CdS　photoelectrode.　The　GO-PAMAM-Fe2+　as　the　neighborhood　component　of　GO-MoS2-CdS-based　photoactive　material　not　only　can　increase　the　loading　amount　of　Fe2+,　but　also　can　inhibit　the　decrease　of　photocurrent　of　GO-MoS2-CdS　by　direct　modification　of　Fe2+　on　the　photoactive　material.　Moreover,　the　high　loading　capacity　of　DNA　hydrogel　can　efficiently　promote　the　performance　of　the　PEC　biosensor.　The　PEC　biosensor　exhibited　satisfactory　analytical　performance　for　OTA　with　a　linear　range　of　0.0001–0.1 ng/mL　and　a　low　detection　limit　of　0.05 pg/mL.　It presents　recommendable　specificity,　stability,　and　practical　applications.　Importantly,　the　PEC　biosensor　provides　a　new　concept　for　construction　of　PEC　biosensing　platform.　Graphical　abstract:　[Figure　not　available:　see　fulltext.].　©　2023,　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　GmbH　Austria,　part　of　Springer　Nature.