Developing　counter　electrode　(CE)　materials　with　outstanding　catalytic　performance　and　low　cost　is　a　critical　step　for　the　large-scale　application　of　dye-sensitized　solar　cells　(DSSCs).　In　this　work,　a　facile　bottom-up　solvothermal　route　followed　by　a　selenization　process　was　introduced　to　synthesize　the　hierarchical　cobalt　nickel　selenides　nanoflowers　(Co-Ni-Se　NFs)　consisted　of　numerous　cross-linked　porous　nanosheets.　The　structure　and　composition　of　Co-Ni-Se　NFs　could　be　regulated　by　simply　tuning　the　feed　molar　ratio　of　Ni/Co.　Profiting　from　the　well　structural　nature,　relatively　large　surface　area,　appropriate　porosity,　optimized　crystal　structure　and　the　synergy　of　multiple　components,　Co-Ni　-Se　NFs　display　superior　catalytic　activity　toward　the　triiodide　reduction.　Impressively,　the　power　conversion　efficiency　(PCE)　of　DSSC　assembled　with　Co-Ni-Se-1:1　NFs　CE　is　9.00%,　which　outperforms　that　of　Pt　CE　(7.97%).　This　strategy　sheds　a　new　light　on　the　controlled　synthesis　of　advanced　hierarchical　materials　for　the　application　in　the　field　of　sustainable　energy.　(C)　2019　Elsevier　B.V.　All　rights　reserved.