Five novel BiIII–thiophenemonocarboxylate (BiIII–TMC) compounds containing pyridinium cations have been synthesized from room‐temperature reactions of bismuth precursors with 2‐thiophenecarboxylic acid (HTMC) and pyridine in water. The structures have been determined by single‐crystal X‐ray diffraction, and two of the compounds have been further characterized by Raman spectroscopy and thermogravimetric analysis. The solid‐state structures of the compounds are built from anionic BiIII building units that vary in nuclearity, overall connectivity, and dimensionality. When using bismuth nitrate at a relatively low metal/ligand ratio, Hpy[Bi(TMC)4(HTMC)] (1) is formed, which consists of mononuclear units charge‐balanced by second coordination sphere pyridinium cations. With increasing metal/ligand ratios, and by consequence, increasing nitrate concentration, nitrate and carboxylate‐bridged chains of [Bi2(TMC)3(NO3)]– units in Hpy[Bi2(TMC)6(NO3)] (2), and nitrate‐bridged [Bi2(TMC)3(NO3)2]2– dimers in Hpy[Bi(TMC)3(NO3)] (3) are isolated. Starting from Bi2O3, polymorphs (Hpy)2[Bi2(TMC)8] (4) and (Hpy)2[Bi2(TMC)8] (5) are formed, both of which contain bismuth centers bridged by carboxylate groups to form dimeric units that are charge‐balanced by pyridinium cations. Presented herein is a discussion of the synthetic conditions over which 1–5 were isolated, and their solid‐state structural chemistry. The thermal stability of 1 and 3, and the spectroscopic characterization of the compounds, are also reported.