In recent decades, flexible and wearable strain sensor has shown promising application prospects in human motion detection, medical rehabilitation, human‐computer interface, etc. Conductive polymer composites (CPCs) composed of conductive fillers and elastic polymers demonstrate the merits of excellent flexibility, high stretchability, and good tensile recovery. They are usually used as flexible strain sensors with large working range and high sensitivity. This review introduces in detail the preparation, morphologies and strain sensing performance of different CPC sensors including one‐dimensional fibers, two‐dimensional films, three‐dimensional foams and hydrogels. CPCs with different structures show their unique advantages in reducing the percolation threshold and/or improving the sensing performance. The multi‐functionalities of CPC strain sensors with extended applications are also reviewed. Finally, we summarize the current challenges and outlook the future development of the CPC strain sensors.