Fiber-type artificial muscles similar to natural muscles are being studied for applications such as robots, prosthetics and exoskeletons. In particular, carbon nanotube (CNT) yarn artificial muscles have attracted interest for their unique mechanical and electrical properties as electrochemical artificial muscles. Here, we demonstrate the large tensile stroke of CNT-based electrochemical yarn artificial muscles induced by increasing capacitance. The coiled graphene/CNT yarns made by the biscrolling method can produce greater tensile actuation using more ions at the same voltage than pristine CNT coils. The maximum tensile actuation of these electrochemical muscles is 19%, which is two times larger than coiled CNT muscles with a work capacity of 2.6 J g−1. These electrochemical artificial muscles could be further developed for practical applications, such as micromechanical devices and robotics.