We report the first Peacock–Weakley type complexes composed of mono‐lacunary Keggin‐type phosphotungstate, [α‐PW11O39]7–, and Bi3+. The self‐assembly reaction between the Keggin‐type phosphotungstate and Bi3+ in aqueous solution produced Peacock–Weakley type 2:1 ([(PW11O39)2Bi]11–, 1) and 1:1 ([PW11O39Bi]4–, 2) complexes depending on the mixing ratio of [α‐PW11O39]7– and Bi3+. Studies of both complexes in solution were conducted by different NMR techniques including 31P and 183W analyses. Complex 1 was successfully isolated as both tetramethyl ammonium (1a) and potassium (1b) salt, and characterized by single‐crystal X‐ray diffraction, IR spectroscopy and elemental analysis. The sandwich structure of 1a and 1b was determined to be constructed by eight Bi–O bonds with two [α‐PW11O39]7– units.