A rotational electromagnetic energy harvester based on a Halbach array (HC-EMEH) with a self-powered Maximum Power Point Tracking (MPPT) circuit is presented in this paper. The magnetic field distribution model of the Halbach array was derived. Based on the law of electromagnetic induction, when the rotor rotates, the coils cut the magnetic induction lines of the Halbach array and produce the AC electric energy. However, the open-circuit voltage at the harvester's output varies with rotational speed. Thus, a maximum power point tracking circuit is designed between the load and harvester to extract the maximum power from a harvester, no matter how the rotational speeds change. The designed MPPT circuit powered by a self-starting circuit can generate stable voltage for the power supply of the MPPT circuit. The experimental results show that the efficiency of the MPPT circuit reaches more than 80%, and the power consumption is only 15 μW when the harvester rotates at 1800 rpm–3000 rpm.