Danger signals, or damage-associated molecular patterns (DAMPs), instigate mitochondrial innate immune responses wherein Mitochondrial Antiviral Signalling protein (MAVS) functions as a key platform molecule to mediate them. The role of MAVS in the pathogenesis of idiopathic pulmonary fibrosis (IPF), however, has not been identified yet. A possibility whether the MAVS signalling can be modulated by currently existing drugs has not been explored, either. Here, using an established model of pulmonary fibrosis, we demonstrate that MAVS plays as a critical mediator of multiple DAMPs signalling pathways and the consequent lung fibrosis after bleomycin-induced injury in vivo After bleomycin injury, the expression of MAVS was mainly observed in macrophages. In addition, multimeric MAVS aggregation, a key event of MAVS signalling activation, was significantly increased and persisted in bleomycin-injured lungs. Interestingly, a proapoptotic BH3 mimetic ABT-263 attenuated the expression of MAVS and its signalling and, consequently, the development of experimental pulmonary fibrosis. In contrast, the therapeutic effects of Pirfenidone or Nintedanib, two approved drugs for IPF treatment, were not related to the modulation of MAVS or its signalling. Importantly, multimeric MAVS aggregation was significantly increased in lungs from the patients with IPF as well. In conclusion, MAVS may play an important role in the development of pulmonary fibrosis, and targeting MAVS with BH3 mimetics may provide a novel therapeutic strategy for IPF, a major unmet disorder.