This paper employs density functional theory to investigate transition metal-doped WSSe(Ti–WSSe, Mn–WSSe, Mo–WSSe) gas-sensitive devices, exploring their adsorption and sensing properties towards three characteristic gases of thermal runaway in Li-ion battery, namely H2, CO, and CO2. Results indicate that Ti, Mn, and Mo dopants preferentially anchor to the S-surface of the pristine WSSe monolayer, exhibiting binding energies of −3.145, −1.282, and −3.376 eV, respectively. All three monolayers present significantly improved sensing characteristics, showing chemisorption towards CO. Band structure and density of states analyses reveals the potential of Ti–WSSe monolayer as a resistive CO detection sensor. Furthermore, recovery time calculations are performed to assess the reuse capabilities of the three gas-sensitive devices. Regarding high sensitivity and tunable detection, Mn–WSSe monolayer emerges as potential candidate for H2 detection, while Mo–WSSe monolayer is more suitable for CO2 detection. This work lays the foundation for the potential gas-sensitive applications of WSSe monolayer in the field of thermal runaway scenarios, which is expected to advance research in gas sensing domains.