Forchlorfenuron (FCF), a Septin2 chemical inhibitor and widely used plant growth regulator in global agriculture, poses potential risks to human health through dietary and environmental exposure. However, the myocardial toxicity and underlying mechanisms of FCF remain unclear. We exposed H9c2 cells and C57BL/6 mice to FCF, then evaluated cardiotoxicity in both in vitro and in vivo settings. Network pharmacology and gene sequencing analyses were employed to explore the mechanism of FCF-induced cardiotoxicity. Our results showed that FCF-induced cell death was linked to oxidative stress, mitochondrial damage, and inflammation in H9c2 cells. In FCF-treated mice, reduced cardiac function, increased myocardial fibrosis, and inflammation were observed. Looking at the underlying mechanisms, our network pharmacology and transcriptome sequencing results show that administering FCF increases NF-κB phosphorylation, which in turn activates the NLRP3/Caspase-1/GSDMD-N pathway. In addition, the NLRP3 inhibitor MCC950 alleviated FCF-induced cardiotoxicity, whereas the NLRP3 agonist nigericin exacerbated FCF-induced cardiotoxicity in vitro and in vivo. Additionally, our findings showed that knocking out Septin2 specifically in the heart did not cause cardiotoxicity in either H9c2 cells or mice, suggesting that FCF-induced cardiotoxicity occurs independently of Septin2 inhibition. Our study provides the evidence that FCF induces cardiotoxicity by activating the NF-κB/NLRP3 inflammasome. This discovery not only elucidates a novel molecular pathway underlying FCF-induced myocardial injury but also offers potential targets for therapeutic interventions, such as inhibitor of NLRP3, which could mitigate the cardiotoxic risks associated with agricultural exposure to FCF and improve public health safety.