<p>The structural stability of multivacancies in monolayer gallium nitride has been studied using density functional theory (DFT) with the generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof for the exchange–correlation functional. The supercell consisting of 72 atomic sites is used to model the multivacancies, with all atoms in the supercell relaxed during optimization. The multivacancies are created by removing a pair of Ga–N atoms sequentially from the center of the supercell, following the part-of-hexagonal-ring method. The multivacancies modeled are monovacancy to hexadecavacancy. The stability of multivacancies is analyzed through the formation and dissociation energies. From the calculated energies, we conclude that hexa- and decavacancies are stable multivacancies, indicating that multivacancies in monolayer GaN tend to agglomerate to hexa- and decavacancies. To show the effect of atomic relaxation, we compare our DFT results with the dangling bond counting model, which ignores atomic relaxation. The symmetry of each defective system is discussed.</p> Graphical Abstract <p></p>