Black crystals of Ag₃Bi₁₄Br₂₁ = (Bi ₉⁵⁺)[Ag₃Bi₃Br₁₅ ^3-]-(Bi₂Br₆^2-), the first argentiferous bismuth subhalide, were obtained from a stoichiometric melt of Ag, Bi, and BiBr₃. The compound crystallizes in the monoclinic space group P2₁/m with lattice parameters a = 1277.78(5) pm, b = 1466.87(6) pm, c = 1342.62(5) pm, and β = 108.47(1)° at 110(5) K. In contrast to all other bismuth subhalides that contain an electron-rich transition metal, the silver atoms are not bonded to bismuth atoms. Instead they are integrated into the anionic bromometallate network, which consists of [MBr₆]- octahedra (M = Ag, Bi) that share edges and vertices. These corrugated _∞²[Ag₃Bi₃Br₁₅] ^3- sheets alternate with tessellated layers formed by Bi ₉⁵⁺ polycations and hitherto unknown (Bi^II ₂Br₆)^2- groups. The latter anions contain Bi₂⁴⁺ dumbbells (299 pm) and can be represented by the structured formula [Br₂Bi^II(μBr)₂Bi ^IIBr₂]^2-. The multi-center bonding within the Bi₉⁵⁺ cluster and the bent single-bond in the Bi ₂ dumbbell can be visualized using the electron localization indicator (ELI-D).