Efficient energy storage devices like rechargeable batteries have a vital role in the modern society to cater for an ever-increasing demand of energy. In this context, magnesium-ion batteries (MIBs) have emerged as high-capacity energy storage systems. However, the progress in this area is hindered due to the lack of suitable anode materials for efficient Mg2+ ion storage and diffusion. In this study, using state-of-the-art density functional theory (DFT) simulations, we have systematically investigated novel one-dimensional Si2BN nanoribbons as anode materials for MIBs applications. Our calculations confirm the structural stability and metallic character of pristine (Si2BN) and hydrogen functionalized (Si2BN-H) nanoribbons upon Mg adsorptions. We find Mg adsorption energies in the ranges of −1.2 to −1.8 (−1.8 to −2.0) eV for 25% (20%) coverages in Si2BN (Si2BN-H), respectively, which are strong enough to mitigate the Mg aggregation. Maximum specific capacities of 661.865 (550.421) mAh g–1 and open-circuit voltages of 0.7–1.1 (0.6–0.8) V are found for Si2BN (Si2BN-H), respectively. Diffusion barrier calculations based on nudge elastic band (NEB) methods reveal a relatively low barrier of 0.14 eV, which guarantees a robust diffusion of Mg ions and faster charge/discharge capability of Si2BN nanoribbons. These intriguing features confirm the potential of functional Si2BN nanoribbons as promising anode materials for MIBs.