The structure of the title compound, [Ni(C₁₀H₈­N₂)₃](S₂O₃)·7H₂O, consists of monomeric Ni(bipy)₃²⁺ cations embedded in an anionic network made up of S₂O₃^2- ions and hydration water molecules. The structure presents the unusual feature of two neighbouring thiosulfates approaching linearly head-to-head with an unusually short S⋯S contact distance of 3.25 Å.