The utilization and selectivity of single atoms have garnered significant attention among researchers. However, it is easy to agglomerate because of its high surface energy. To overcome this challenge, it is crucial to seek suitable carriers to anchor metal single atoms to achieve their optimal performance. In this work, the structures of transition metal single atoms embedded in hexagonal boron nitride (MB₂N₂, M=Fe, Co, Ni, Cu, Zn) are constructed and used for the adsorption and sensing of lithium battery thermal runaway gases (H₂, CO, CO₂, CH₄) through DFT method. The adsorption behavior of MB₂N₂ was evaluated through adsorption energy, sensitivity, and recovery time. The calculation results indicate that CoB₂N₂ exhibits strong adsorption capacity for both H₂ and CO. The sensitivity of FeB₂N₂ toward CO is as high as 3.232×10¹⁶. Subsequently, the adsorption mechanism was studied through TDOS and PDOS, and the results showed that the hybridization between orbitals enhanced the gas adsorption performance. This study presents novel approaches for designing single atom carriers and developing MB₂N₂ sensors for detecting lithium battery thermal runaway gases.