The asymmetric unit of the title compound, 3(C13H24N3)+ [Bi2I9]3−, comprises two cations and one half of a [Bi2I9]3− ion. The C—N bond lengths of the CN3 units in both cations range from 1.336 (3) to 1.364 (5) Å, indicating partial double-bond character pointing towards charge delocalization within the NCN planes. All five-membered rings adopt an envelope conformation with the C atoms as the flap. One of the pyrrolidine rings (cation I) is disordered over two alternative envelope conformations. Two sets of positions were found for two of the methylene groups with an occupancy ratio of 0.757 (10):0.243 (10). The second disordered pyrrolidine moiety (cation II) is disordered around a twofold rotation axis and exhibits two half-occupied symmetry equivalent counterparts. The two BiIII ions are coordinated by six iodide ions in a distorted octahedral manner, with the Bi–I bond lengths ranging from 2.9544 (2) to 3.2414 (2) Å. Two [BiI6]3− octahedra are fused together through face-sharing, forming a dinuclear [Bi2I9]3− unit. The bond lengths of bismuth to the terminal iodides [2.9544 (2)–2.9889 (2) Å] are shorter than the bridging ones [3.1450 (2)–3.2414 (2) Å].