Developing an efficient adsorbent with optimal absorption capacity for carbon dioxide (CO₂) has always been a significant issue. Recently, single-atom adsorbents (SAAs) have been highlighted with special interest as a promising material with a wide range of applications. Nevertheless, comprehending the intricate mechanisms of gas adsorption on SAAs remains an enormous challenge. Herein, we have systematically evaluated the adsorption mechanisms over the transition metals (Fe, Co, Ni, Cu, and Zn) embedded onto the graphdiyne-like boron nitride monolayer using density functional theory calculations. Results show that SAAs exhibit a promoted capacity compared to the pristine graphdiyne-like boron nitride monolayer, mainly ascribed to the electron donation and back-donation mechanism between metal and CO₂. Further, BNene/Fe is favorable for CO₂ adsorption with the strongest interaction energy (−20.7 kcal mol⁻¹). We hope this work will facilitate the design of SAAs in the field of gas adsorption.