© 2019 IEEE. This paper reports a bandwidth enhancement technique using a voltage-boost rectifier (VBR) circuit for vibrational energy harvesters (VEHs). Unlike existing methods that focus on mechanical structures for resonance or tuning circuits, we employ the VBR circuit that rectifies and boosts small output AC voltages of VEHs (Vpp < 1 V) at low frequency (< 1 kHz) to a DC voltage of effective level for the operation of the subsequent circuitry. The developed VBR circuit is experimentally evaluated with a MEMS electret VEH. Compared with conventional diode rectifies, the developed circuit has nearly threefold bandwidth for both 1.0-V and 3.3-V DC outputs with the minimum excitation acceleration of 1 mG (G = 9.8 m/s2).