We report on the high-pressure synthesis of BiMn 7 O 12, a manganite displaying a “quadruple-perovskite” structure. Structural characterization of single-crystal samples shows a distorted and asymmetrical coordination around the Bi atom due to presence of the 6 s 2 lone pair, resulting in noncentrosymmetric space group I m, leading to a permanent electrical dipole moment and ferroelectric properties. On the other hand, magnetic characterization reveals antiferromagnetic transitions in agreement with the isostructural compounds, and the dielectric constant shows anomalies matching the magnetic transition temperatures. BiMn 7 O 12 is therefore a promising multiferroic material, with evidence of coupling between magnetic and dielectric properties.