Red crystals of the title salt, [K(C12H24O6)][Sb(C6H5)2], were obtained by the reaction of SbPh3, KSnBi and 18-crown-6 in liquid ammonia. The asymmetric unit contains one half of a [K(18-crown-6)]+ cation and one half of an SbPh2- anion, with the central element lying on a twofold axis and a centre of inversion, respectively. In the crystal structure, the sequestered potassium cations show weak inter­actions with the [pi]-electrons of the phenyl groups of the SbPh2- anion [shortest K...C distances = 3.190 (2) and 3.441 (2) Å], leading to one-dimensional strands along the crystallographic c axis. These strands are aligned in a pseudo-hexa­gonal packing perpendicular to the ab plane.