•A novel electromechanical structure is proposed for active ground motion isolation.•State of the art disturbance rejection at the subnanometer scale for heavy loads (up to 50kg) is achieved.•A 13dB attenuation of the ground motion is obtained between 12Hz and 100Hz. Vibration isolation is a critical issue in various precision engineering fields. A new design of an active isolation system operating heavy loads (up to 50kg) is presented in this work. This system provides state of the art vibration isolation at the nanometer scale for magnets of a future particle accelerator and is more compact than other studies in this field. The choice of sensors and actuators, the mechanical design and the acquisition electronics are investigated in order to reject ground motion efficiently. A dynamic experimental characterization is performed. Based on the identified model, a specific controller, giving an attenuation between 10Hz and 100Hz was designed and experimentally qualified.