Background Despite its high lesion accessibility and versatility, endoscopic platforms have suffered from designing flexible manipulators with high payload capability sufficient to perform advanced endoscopic procedures. Methods A flexible robotic platform, K-FLEX, has been developed with a design of 17 mm in overall diameter. To overcome the shape distortion and deflection in payload handling, a strong continuum manipulator has been designed to have maximum resistance to the distortion. The kinematic analysis and mapping strategy have been established for the master-slave teleoperation. Results The proposed manipulator has shown 7.5 mm in trajectory variation to lift the weight of 300 g. Finally, the feasibility of the integrated K-FLEX system has been verified through three kinds of simulated surgical tasks. Conclusions The initial prototype of the proposed robot showed the possibility of advanced endoscopic surgery with improved payload capability.