Objectives: Baicalein, a flavonoid derived from the roots of Scutellaria baicalensis Georgi, demonstrates multifarious pharmacological effects due to its high antioxidant activity. However, the latent mechanisms remain insufficiently resolved. In the present research, we evaluated the therapeutic effects of baicalein on isoprenaline (ISO)-induced heart failure and investigated the possible underlying mechanisms. Methods: Toxicity was analyzed in zebrafish embryos and mouse atrial myocytes HL-1. The MTT assay was used to evaluate the effectiveness of baicalein. DCFH-DA was used as a fluorescence probe to detect intracellular reactive oxygen species (ROS). Superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) levels were measured using SOD, MDA and GSH-Px commercial kits. Adult BALB/c mice were randomized into six groups of ten animals each. Cardiac function was analyzed by echocardiographic images. Structural changes were analyzed by hematoxylin & eosin (HE) staining, Masson staining and TUNEL staining. The mechanism of baicalein was investigated by analyzing relative signaling pathways through western blotting. Results: Our studies show that baicalein both significantly reduces ISO-induced oxidative stress, apoptosis and cardiac fibrosis in vitro and vivo, this phenomenon was related to mitochondrial fusion/fission balance and inhibiting GRP78/CHOP pathway. Conclusions: Our results suggested that baicalein controls mitochondrial fusion/fission balance and inhibits GRP78/CHOP pathway, thus exerting therapeutic effects in ISO-induced heart failure in HL-1 cells and BALB/c mice. These results suggested that baicalein may be a potential therapeutic agent for heart failure.