In recent years, there has been significant research interest in flexible supercapacitors as energy storage devices for enhancing wearable and portable electronics. This is due to their lightweight nature, high power density, excellent cyclic durability, fast charge/discharge rate, and robust mechanical integrity. Flexible supercapacitors offer the potential to revolutionize the field of energy storage by providing efficient and reliable power sources for various portable and wearable applications. Thin film based electrodes, as one of the ingredients of flexible supercapacitors, have a considerable role on the electrochemical performance of flexible supercapacitors. Tungsten oxide (WO3), a transition metal oxide (TMO), is a highly desirable electrode material for flexible supercapacitor applications. It offers several advantages, including low cost, environmental friendliness, inherent conductivity, versatile oxidation states, and high theoretical capacity. These properties make WO3 an excellent choice for developing efficient and sustainable energy storage solutions. Specially, this review provides current developments on the WO3 based thin film electrodes toward flexible supercapacitors. We will present the focus attention on the charge storage mechanisms, fabrication strategies, and characterization methods employed in this field.