•A novel octanuclear heterometallic {Ni6WNi}-substituted phosphotungstate•Spoon-shaped monomeric polyoxometalate with mixed organic ligands and {Ni6WNi} cluster core•The {Ni6WNi} core containing unique WO4 tetrahedral linkerA novel octanuclear heterometallic {Ni6WNi}-substituted Keggin-type phosphotungstate [Ni(H2O)(en)2][WO4]{[Ni6(OH)3(H2O)2(en)3(Im)2](B-α-PW9O34)}·2H2O (1) with mixed organic ligands of en and Im (en = ethylenediamine, Im = Imidazole) has been hydrothermally synthesized and structurally characterized by IR spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. Notably, 1 is an interesting spoon-shaped monomeric polyoxometalate consisting of mixed organic ligands and unprecedented octanuclear heterometallic {Ni6WNi} cores where the WO4 tetrahedron is linked to the triangular {[Ni6(OH)3(H2O)2(en)3(Im)2](B-α-PW9O34)} clusters and [Ni(H2O)(en)2]2 + cations through Ni–Ot–W linkages. Magnetic susceptibility measurements indicate ferromagnetic coupling within 1.A unique novel octanuclear heterometallic {Ni6WNi}-substituted Keggin-type phosphotungstate [Ni(H2O)(en)2][WO4]{[Ni6(OH)3(H2O)2(en)3(Im)2](B-α-PW9O34)} · 5H2O (1, en = ethylenediamine, Im = Imidazole) has been hydrothermally made. It is an interesting spoon-shaped monomeric polyoxometalate containing {Ni6WNi} cores linked by the WO4 group, observed firstly in polyoxometalate chemistry.