Abstract Body: Objective: Cardiac fibrosis plays a critical role in the progression toward heart failure following myocardial ischemia (MI). Activation of fibroblasts to myofibroblasts is a central driver of fibrotic remodeling; however, the molecular mechanisms that regulate this process remain incompletely understood. Although transcriptional pathways involved in cardiac fibrosis have been extensively studied, the role of epigenomic (post-transcriptional) regulation, such as N6-methyladenosine (m6A), in fibrotic remodeling remains unclear. Here, we investigated whether METTL3-dependent m6A methylation regulates fibronectin (FN1) expression and contributes to cardiac fibrosis following MI. Methods: Myofibroblast-specific METTL3 conditional knockout mice were subjected to sham or MI surgery. Cardiac function was assessed by echocardiography, and fibrosis was evaluated using histology and molecular analyses. FN1 and other ECM molecules were measured by qPCR, Western blotting, and immunohistochemistry. mRNA stability was assessed using Actinomycin D-chase assays. m6A enrichment on FN1 transcripts was determined by MeRIP and CUT&RUN was used to identify METTL3-associated regulatory regions. Pharmacological inhibition of METTL3 with STM2457 was used to validate findings in vivo. Results: Ischemic injury resulted in a significant global m6A methylation. MeRIP followed by FN1 gene expression demonstrated significant enrichment of m6A methylation. Myofibroblast-specific METTL3 deletion markedly reduced FN1 expression and significantly attenuated cardiac fibrosis post-MI. Consistently, pharmacological inhibition of METTL3 using STM2457 improved cardiac function & reduced fibrotic remodeling following MI. mRNA stability assays further demonstrated that ischemia-induced m6A methylation enhances the stability of FN1 transcripts. Furthermore, CUT&RUN analysis identified multiple mRNA methylation sites within FN1 mRNA. Conclusions: These findings identify METTL3-dependent m6A RNA methylation as a key regulator of fibronectin mRNA stability and fibrotic remodeling following myocardial ischemia. Targeting METTL3-mediated RNA methylation may represent a potential therapeutic strategy to limit cardiac fibrosis after ischemic injury.