Background: Inflammation and oxidative stress play predominant roles in the initiation and progression of ischaemia/reperfusion (I/R) injury, with nuclear factor kappa B (NF-κB) serving as a crucial mediator. Overexpression of the inhibitor of κB alpha (IκBα) gene is hypothesized to have protective effects against apoptosis and autophagy in cardiomyocytes subjected to hydrogen peroxide (H 2 O 2) by inhibiting the NF-κB pathway. Methods: The IκBα S32A, S36A gene was transfected via adeno-associated virus serotype 9 (AAV9) delivery into neonatal rat ventricular cardiomyocytes (NRVMs) prior to H 2 O 2 treatment. NRVMs were divided into control, H 2 O 2 , GFP + H 2 O 2 , IκBα+H 2 O 2 , and pyrrolidine dithiocarbamate (PDTC) + H 2 O 2 groups. Nuclear translocation of the NF-κB p65 subunit was evaluated by immunofluorescence and Western blotting. Cell viability was assessed by Cell Counting Kit-8 assay. Supernatant lactate dehydrogenase (LDH) and intracellular malondialdehyde (MDA) were measured to identify H 2 O 2-stimulated cytotoxicity. Apoptosis was determined by Annexin V-PE/7-AAD staining, and the mitochondrial membrane potential (ΔΨm) was detected by JC-1 staining. Western blotting was used to detect apoptosis-and autophagy-related proteins. Results: IκBα transfection significantly increased cell viability and ΔΨm but decreased the supernatant LDH and cellular MDA levels in cardiomyocytes exposed to H 2 O 2. Meanwhile, IκBα overexpression decreased H 2 O 2-induced apoptosis by upregulating the Bcl-2/Bax ratio and reduced autophagy by downregulating the expression of Beclin-1 and the LC3-II/LC3-I ratio. These effects partly accounted for the ability of IκBα to inhibit the NF-κB signalling pathway, as evidenced by decreases in p65 phosphorylation and nuclear translocation. Indeed, the effects of inactivation of NF-κB signalling with the specific inhibitor PDTC resembled the cardioprotective effects of IκBα during H 2 O 2 stimulation.