Low-frequency human motions pose a significant challenge for energy harvesters. Hence, an electromagnetic-flexible piezoelectric energy harvester (E-FPEH) with an eccentric pendulum has been developed in this study. The E-FPEH consists of an eccentric pendulum with a magnet array, plectrums, coil groups, and a fixture with a piezoelectric beam. The E-FPEH harvests mechanical energy through changes in magnetic flux and the large deformation of piezoelectric material. During the eccentric pendulum swinging, the magnet array goes through the coil to operate the electromagnetic energy harvester (EMH), while the plectrums pluck the piezoelectric beam, driving the piezoelectric energy harvester (PEH). The two harvesters are verified using a motor with uniform circular motion linked to the prototype. Finite element simulations of the EMH show that the numerical output voltage is consistent with the experimental one. Meanwhile, the theoretical model is provided to verify the output characteristics of the PEH. Then, the E-FPEH works at linear motor which derives excitation about 2 Hz, 100 mm. As a result, the EMH achieves a maximum RMS voltage of 0.35 V and an average power output of 1176 μW over four cycles. For the PEH, the maximum RMS voltage is 0.56 V, with an average power output of 1.74 μW per oscillation cycle. The E-FPEH records maximum load voltages of 1.225 V and 3.07 V, respectively. Overall, the E-FPEH is designed for low-frequency human motions.