The rapid development of wearable electronic devices has promoted the research of flexible supercapacitors. Conducting polymers have shown great application potential in flexible supercapacitors due to their high conductivity, fast and reversible redox reaction, and flexibility similar to traditional polymer materials. Pure conducting polymers electrodes exhibit limited electrochemical performance (short cycling life and low actual capacity), and the formation of composite materials with emerging two-dimensional materials can improve their electrochemical performance. The preparation and assembly strategies of two-dimensional materials (graphene, transition metal chalcogenides, and transition metal carbon/nitride) composites from one to three dimensions is discussed firstly, and then the latest progress in their application in flexible supercapacitors with different structures (fiber structure, sandwich structure and planar interdigital structure) is reviewed. Finally, the challenges and future development trend of conducting polymer matrix composites in flexible supercapacitors are presented.