AbstractA chemical reaction between Sb and N₂ was induced under high‐pressure (32–35 GPa) and high‐temperature (1600–2200 K) conditions, generated by a laser heated diamond anvil cell. The reaction product was identified by single crystal synchrotron X‐ray diffraction at 35 GPa and room temperature as crystalline antimony nitride with Sb₃N₅ stoichiometry and structure belonging to orthorhombic space group Cmc2₁. Only Sb−N bonds are present in the covalent bonding framework, with two types of Sb atoms respectively forming SbN₆ distorted octahedra and trigonal prisms and three types of N atoms forming NSb₄ distorted tetrahedra and NSb₃ trigonal pyramids. Taking into account two longer Sb−N distances, the SbN₆ trigonal prisms can be depicted as SbN₈ square antiprisms and the NSb₃ trigonal pyramids as NSb₄ distorted tetrahedra. The Sb₃N₅ structure can be described as an ordered stacking in the bc plane of bi‐ layers of SbN₆ octahedra alternated to monolayers of SbN₆ trigonal prisms (SbN₈ square antiprisms). The discovery of Sb₃N₅ finally represents the long sought‐after experimental evidence for Sb to form a crystalline nitride, providing new insights about fundamental aspects of pnictogens chemistry and opening new perspectives for the high‐pressure chemistry of pnictogen nitrides and the synthesis of an entire class of new materials.