When ω c = 1185cm -1 , the emission of a photon can pro-mote two molecular vibrational transitions (due to the broadening effect caused by the environment): v mol 1 → v mol 2 with an energy difference ∆ε mol 1→2 = 1140cm -1 and v mol 0 → v mol 3 with ∆ε mol 0→3 = 1238cm -1 , as shown by the blue-shaded region in Fig. . Simultaneously, the cavity mode is thermalized by its coupling to the cavity photon bath, and the molecular wave packet quickly tunnels to the right well on the vibrationally excited states. Subsequently, after the tunneling, the relaxation from the vibrationally excited state to the low-lying state (v mol 2 → v mol 1 and v mol 3 → v mol 0 ) in the product region excites a photon in the cavity mode, which then leaks to the cavity bath, as shown in the yellow-shaded area in Fig. . Therefore, the molecular vibrational heating/cooling is energetically fueled by the cavity photon bath through the mediation of a resonant cavity mode. After a cavity-induced cotunneling process is accomplished, the population of different vibrational levels remains the same. If this additional reaction channel interferes constructively with other pathways in Fig. (a), the reaction rate is increased. Furthermore, this enhancement effect on the rate becomes more pronounced at higher temperatures, where the likelihood of populating the photonic excited states is increased, as presented in the SI.