This paper proposes a fuzzy control (FC) algorithm for a pendulum-driven cart (PDC) system. The PDC is a mechanism that represents a novel driving concept of ground mobile robot which only employs internal thrust and static friction. The control objective of the system is to drive the cart towards a desired direction by swinging the pendulum only. The proposed FC algorithm is designed based on the closed-loop control algorithm proposed in Yu et al. (2008a). Simulation results are presented to demonstrate the effectiveness of the proposed algorithm. A prototype of the PDC system developed by using the LEGO Mindstorms kit and the ROBOLAB Software is also presented in the paper. The experimental results demonstrate that the PDC system is realisable, and the proposed FC algorithm is simple and effective.Reference to this paper should be made as follows: Liu, Y. and Yu, H. (2012) 'Fuzzy control of an underactuated pendulum-driven cart system', Int. He has extensive research experience in modelling and control of robots and mechatronics devices and neural networks, mobile computing, modelling, scheduling, planning and simulations of large discrete event dynamic systems, RFID with applications to manufacturing systems, supply chains, transportation networks and computer networks. He has published over 140 research papers and held several grants from EPSRC, the Royal Society, and other funding bodies. He is a member of the EPSRC Peer Review College and serves on various conferences and academic societies.