Idiopathic pulmonary fibrosis (IPF) is a fatal disease with high mortality and limited effective therapy. Herein, we reported that fluvoxamine, a selective serotonin reuptake inhibitor (SSRI), used in depression and anxiety treatment, also exhibited therapeutic activities in IPF. Fluvoxamine inhibited cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING), restrained the activation of their downstream targets, including PERK/ eIF2α/ c-Myc/ miR-9–5p/ TBPL1 and TBK1/ YAP/ JNK1/2/ Bnip3/ CaMKII/ cofilin signaling, thus attenuated the activation and migration of fibroblasts upon TGF-β1 challenge. Fluvoxamine dose-dependently improved pulmonary function, decreased the expression of inflammatory factors, reduced excessive production of extracellular matrix, and thus alleviated bleomycin (BLM)-induced lung fibrosis in mice. Moreover, fluvoxamine at a dose of 10 mg/ kg showed similar efficacy as pirfenidone (PFD) at a dose of 30 mg/kg in a mice model of lung fibrosis. In summary, our results suggest that fluvoxamine is an effective anti-fibrotic agent for IPF.