Abstract Background Cardiac fibrosis is significant global health problem, which is associated with numerous cardiovascular diseases, and ultimately leads to the progression to heart failure. β-adrenergic receptor (β-AR) overactivation play a role in the development of cardiac fibrosis. Miglustat (Mig) has shown anti-fibrosis effects in multiple fibrotic diseases. However, it is unclear whether and how Mig can ameliorate cardiac fibrosis induced by β-AR overactivation. Methods In vivo, mice were injected with isoproterenol (ISO) to induce cardiac fibrosis and treated with Mig. In vitro, primary cardiac fibroblasts were stimulated by ISO and treated with Mig. Levels of cardiac fibrosis, cardiac dysfunction, activation of cardiac fibroblasts were evaluated by real-time polymerase chain reaction, western blots, sirius red staining, immunohistochemistry staining and echocardiography. Through GEO data and knockdown UDP-glucose ceramide glycosyltransferase (UGCG) in primary cardiac fibroblasts, whether Mig alleviates cardiac fibrosis by targeting UGCG was explored. Results The results indicated that Mig alleviated ISO-induced cardiac dysfunction. Consistently, Mig also suppressed ISO-induced cardiac fibrosis. Moreover, Mig attenuated ISO-induced cardiac fibroblasts (CFs) activation. To identify the protective mechanism of Mig on cardiac fibrosis, several classical β-AR downstream signaling pathways, including ERK, STAT3, Akt and GSK3β, were further analyzed. As expected, ISO activated the ERK, STAT3, Akt and GSK3β in both CFs and mouse hearts, but this effect was reversed pretreated with Mig. Besides, Mig ameliorates ISO-induced cardiac fibrosis by targeting UDP-glucose ceramide glycosyltransferase (UGCG) in CFs. Conclusions Mig ameliorates β-AR overactivation-induced cardiac fibrosis by inhibiting ERK, STAT3, Akt and GSK3β signaling and UGCG may be a potential target for the treatment of cardiac fibrosis.