A novel two-dimensional graphdiyne (GDY)-like B–N–C compound (BNDY) is designed. The investigation of the adsorptive, electronic, magnetic, and optical properties of lithium (Li) on BNDY reveals several intriguing discoveries. BNDY exhibits slightly lower Li adsorption energy and smoother diffusion barriers than GDY, suitable for rapid Li mobility. Following the adsorption of Li, charge transfers from Li to B, N, and C atoms along the C chain containing alkyne bonds, ultimately transforming the systems from p-to n-type semiconductors. Notably, it also induces a spin-splitting phenomenon, resulting in the generation of magnetic moments. Moreover, the absorption coefficient and reflectivity of BNDY with Li adsorption decrease in the infrared and visible regions, while maintaining high in the near ultraviolet range. In conclusion, BNDY is suitable for fast-charging/discharging Li-ion batteries, and Li adsorption plays an important role in modulating BNDY's properties, providing a theoretical foundation for applications in spintronic and optoelectronic devices.