Hierarchical　structure　design　and　use　of　cocatalyst　are　effective　strategies　to　improve　the　photocatalytic　performance　of　semiconductor　catalysts.　Herein,　0D　NiSe2　nanoparticles　decorated　2D　ZnIn2S4　ultrathin　nanosheet-assembled　microflowers　using　a　facile　solvothermal　approach　are　synthesized.　The　as-obtained　NiSe2/ZnIn2S4　nanocomposites　exhibit　enhanced　visible-light　photocatalytic　H2-evolution　activity　of　1487 µmol　(g　h)–1,　three　times　higher　than　that　of　pure　ZnIn2S4.　The　hierarchical　structure　of　ZnIn2S4　microflowers　exposes　more　surface-active　sites　and　enhances　light　harvesting.　Meanwhile,　the　formation　of　heterojunctions　between　ZnIn2S4　nanosheets　and　NiSe2　nanoparticles　creates　a　space-charge　separation　region　that　facilitates　the　transfer　and　separation　of　photoinduced　electrons　and　holes,　resulting　in　improved　photocatalytic　H2　production.　This　work　provides　a　promising　strategy　for　designing　and　constructing　0D/2D　heterojunctions　for　efficient　solar-driven　energy　conversion.　©　2021　Wiley-VCH　GmbH