Circular RNAs (circRNAs) have been linked to the pathophysiology of metabolic disorders such as dyslipidemia, non-alcoholic fatty liver diseases (NAFLD), and type 2 diabetes (T2D). Dysregulated circRNA levels impact inflammation, insulin sensitivity (IS), and the metabolism of fats and carbohydrates. Hence, targeting these circRNAs can be beneficial in modulating adipogenesis, fat metabolism, and insulin resistance (IR) associated with obesity. Moreover, obesity-associated malignancies, such as colon, liver, and breast malignancies, were also associated with altered circRNA expression. Dysregulated circRNAs can impact tumor growth, metastasis, and chemoresistance via signaling pathways, cell cycle, and apoptosis affection. In this book chapter, we comprehensively discuss circRNAs in the context of obesity, their involvement in thermogenesis, and their role in mediating obesity-associated malignancies.