Conducting polymers (CPs) constitute an important class of organic functional materials. Their unique physical and electrical properties and being inexpensive, easy to synthesize, and suitable matrices for biomolecule immobilization have enabled them to find a wide range of use, including playing roles in supercapacitors, batteries, electrochromic devices, solar cells, sensors, and biomedical applications. To enhance the performance of the CPs, various composite materials have been synthesized with carbon-based materials, metals or metal oxides, etc. This review comprehensively discusses CPs and their composites, followed by their applications. The purpose of this review is to summarize the electrochemical sensors that are based on CPs and their composites and to address future aspects of electrochemical sensing materials.