Abstract <p>Density functional theory (DFT) was exploited to calculate the structural and elastic characteristics of lithium-doped boron nitride nanoribbons (BNNRs). The calculations utilized the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method with Generalized Gradient Approximation (GGA) for the exchange-correlation functional. The data indicates that the cohesive energy of pure and lithium-doped zigzag boron nitride nanoribbons (<i>n</i>-ZBNNRs) (<i>n</i> = 6 and 8) increases with the width of the nanoribbons. Furthermore, wider pure and doped nanoribbons are more stable than narrower BNNRs. The pure and lithium-doped boron nitride nanoribbons are insulators, and the bandgap also increases as the width of the nanoribbons decreases. Additionally, the lithium-doped nanoribbons have smaller gaps. Our calculations suggest that the shear modulus of pure and doped nanoribbons is lower than that of graphene nanoribbons (GNRs). The positive Poisson’s coefficient vectors of pure and lithium-doped <i>n</i>-ZBNNRs (<i>n</i> = 6 and 8) predict that elongating the nanoribbons in specific directions reduces the nanoribbon’s width. The negative Poisson’s coefficient vectors in these directions indicate that the simulated nanoribbons behave like auxetic materials. The data show that lithium doping significantly decreases the three moduli of elasticity.</p>