Recently, flexible electrochemical biosensors have been attracting more and more attentions throughout the world both in academia and industry, because of its leading role in the development of efficient, miniaturized, rapid and user-friendly device towards health monitoring, environmental microsense systems and defense systems. Herein, we shine a light on the advances in flexible electrochemical biosensors by tracking the developments of novel carbon nanomaterials based smart device design and versatile applications. Particularly, the flexible electrochemical biosensors either with supported substrates or free-standing are summarized. We start from retrospection on the outlook of the field and highlight the direction of flexible electrochemical biosensors in the areas of healthcare, security and environmental monitoring. And then we review the recently developed fabrication approaches with discussing the state-of-art findings for each category. It is believed that the flexible electrochemical biosensors will play a more and more pivotal role in the emergent body sensor networks arena with the fast development of carbon nanomaterials and smart devices design.