This study proposes a novel MRI-powered robotic system controlled with the magnetic field generated by a magnetic resonance imaging (MRI) scanner. In the proposed system, we use an MRI-powered actuator unit proposed in the previous study and a spherical positioning mechanism. The actuator unit contains a ferromagnetic sphere, which acts as a power source and is used to control the positioning unit inside the MRI environment. These elements enable the development of a remote needle tip positioning system for use within the MRI scanner. Potential applications of the developed system include the automation of procedures during under MRI inspections, especially the cryoablation of breast cancer. In this paper, we report on the performance evaluation and the MR-safety of the proposed system and describe the newly developed spherical positioning mechanism, which can be activated by the actuator units.