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.　©　2019　Elsevier　B.V.