Base isolator is one of the most adopted and effective means of mitigating unwanted and harmful vibrations to protect buildings and other key civil infrastructure from seismic events. For this reason, the base isolation technology has advanced greatly in recent years, especially the magnetorheological elastomer (MRE) isolator. However, the operation of such an MRE isolator needs external power supply to be activated, which may fail due to the power outage caused by the seismic movement. To this end, this work developed an MRE base isolation system with self-powering capability. This characteristic enables the isolation system self-sufficient without relying on external power. The self-powering component is an innovative omnidirectional element and can collect vibration energy from all horizontal directions. In addition, the self-powered isolation system performs rate-dependent softening behaviour which overcomes the conflicting requirements that the stiffness is required to be hard during daily operation but soft when the earthquake happens. For this reason, this new isolation system has been built and tested, including its MRE isolator and self-powering components. Its vibration reduction capability for building is also investigated on a scaled building. The theoretical analysis and verification is also performed and the conclusions coincide with the experimental results. The experimental and simulation results demonstrate that this new isolation system is capable of generating electricity which is sufficient to power itself when it is subjected to ground motions, and that it shows a high effectiveness in reducing the floor accelerations and the relative displacement.