A series of new heterometallic niobium–molybdenum iodido complexes were synthesized from a polymeric precursor by cluster excision technique: [Mo5NbI8(H2O)3(OH)3]·2H2O, trigonal space group R\bar{3}c (No. 167), a = 9.6859(2), b = 9.6859(2), c = 43.6282(14) Å, Z = 6, V = 3544.69(20) Å3, K3[Mo5NbI8(OH)6]·11H2O, triclinic space group P\bar{1} (No. 2), a = 9.5522(10), b = 12.2871(14), c = 16.0484(14) Å, α = 90.141(3), β = 91.409(3), γ = 107.798(3) °, V = 1792.8(3) Å3, Z = 4, K[Mo5NbI8(H2O)2Cl4], orthorhombic space group Cmca (No. 64), a = 9.3906(4), b = 16.7816(10), c = 16.0314(9) Å, Z = 4, V = 2526.4(2) Å3, (Pr4N)3[Mo5NbI8(CN)6], cubic space group Im\bar{3}m (No. 229), a = 14.96850(10) Å, Z = 2, V = 3353.78(4) Å3. Syntheses, X‐ray crystal structures, and electronic structures of the new compounds are discussed in this article.