Long-term exposure to arsenic (As), which is a ubiquitous environmental contaminant, significantly enhances the risk of multiple cancers, including bladder and lung cancers. In recent years, the important roles of circular RNAs (circRNAs) in tumorigenesis and development have attracted widespread attention. However, the specific molecular mechanisms by which circRNAs promote bladder cancer development following exposure to arsenic remain incompletely understood. This study is the first to demonstrate that circPDE3B is significantly upregulated in a cell model of transformation triggered by arsenic and that it promotes this transformation process. Our study elucidated the biological function of circPDE3B in vitro, in SV-HUC-1 cells, showing that it accelerates the malignant transformation from arsenic via increasing cell proliferation and inhibiting apoptosis. Furthermore, we delineated a novel molecular mechanism whereby circPDE3B directly binds to NF-κB and STAT3, inhibiting their ubiquitination and increasing their stability. This, in turn, affects downstream HIF-1α expression, promoting the malignant transformation of SV-HUC-1 cells and eventually resulting in bladder carcinogenesis. Our research reveals the critical regulatory role of circPDE3B in the arsenic-triggered malignant transformation within SV-HUC-1 cells. This study offers broader perspectives on the molecular mechanisms driving bladder cancer progression, while also identifying potential targets for early diagnosis and treatment of bladder tumour.