Energy harvesting becomes an effective method for self-powering systems in wireless applications for improved observation and measurements. However, traditional scavenging techniques cannot generate enough energy for proper operation under low-frequency ambient vibration. We present a frequency up-converter vibration energy harvester from low-frequency external vibrations. The harvester converts low-frequency vibrations to high-frequency self-oscillations through a mechanical frequency up-converter using magnetic coupling, thus providing more efficient energy conversion at low frequencies. The harvester consists of two cantilever beams with tip magnets facing each other at the same polarity. The low-frequency beam is made of polymer, while the high-frequency beam is made of Aluminum. The high-frequency beam is a bimorph fully covered with piezoelectric layers. A lumped parameter of two degree of freedom model is presented to simulate the dynamic behavior and the generated voltage signal. The static response of the resonators shows a threshold distance of 15mm between the two magnets where the system has monostable oscillates above the threshold and bistable oscillations below the threshold. Furthermore, the dynamic behavior for the resonators is investigated at monostable, threshold, and bistable regions for different excitation levels. The harvester’s output voltage at different resistance values is extracted from the model. frequency up-converting can effectively scavenge energy from low-frequency external vibrations by mechanically up-converting the ambient vibration frequency.