A major challenge for miniature bioelectronics is wireless power delivery deep inside the body. Electromagnetic or ultrasound waves suffer from absorption and impedance mismatches at biological interfaces. On the other hand, magnetic fields do not suffer these losses, which has led to magnetically powered bioelectronic implants based on induction or magnetothermal effects. However, these approaches have yet to produce a miniature stimulator that operates at clinically relevant high frequencies. Here, we show that an alternative wireless power method based on magnetoelectric (ME) materials enables miniature magnetically powered neural stimulators that operate up to clinically relevant frequencies in excess of 100 Hz. We demonstrate that wireless ME stimulators provide therapeutic deep brain stimulation in a freely moving rodent model for Parkinson's disease and that these devices can be miniaturized to millimeter-scale and fully implanted. These results suggest that ME materials are an excellent candidate to enable miniature bioelectronics for clinical and research applications. Display omitted •Magnetoelectric materials enable millimeter-sized wireless stimulators•Wireless neural stimulators reach therapeutic frequencies in freely moving rodents•Miniature bioelectronic devices treat Parkinson's disease in a rat model Magnetoelectric (ME) materials enable tiny remotely powered neural stimulators. Singer et al. demonstrate that alternating magnetic fields can power millimeter-sized ME stimulators in freely moving rodents. The extreme miniaturization made possible by this technology lays the foundation for a new class of minimally invasive bioelectronics.