The new narrow-band red-emitting phosphor material Sr₄[LiAl₁₁N₁₄]:Eu²⁺ was synthesized by solid-state reaction using a tungsten crucible with a cover plate in a tube furnace. When excited with blue light (460 nm), it exhibits red fluorescence with an emission maximum at 670 nm and a full width at half-maximum of 1880 cm^–1 (∼85 nm). The crystal structure was solved and refined from single-crystal X-ray diffraction data. This new compound from the group of the nitridolithoaluminates crystallizes in the orthorhombic space group Pnnm (No. 58) with the following unit-cell parameters: a = 10.4291(7) Å, b = 10.4309(7) Å, and c = 3.2349(2) Å. Sr₄[LiAl₁₁N₁₄]:Eu²⁺ shows a pronounced tetragonal pseudo-symmetry. It consists of a framework of disordered (Al/Li)N₄ and AlN₄ tetrahedra that are connected to each other by common corners and edges. Along the [001] direction, the tetrahedral network creates empty four-membered-ring channels as well as five-membered-ring channels, in which the Sr²⁺ cations are located.