In this paper, we propose a low-frequency (<100 Hz) piezoelectric MEMS energy harvester (PMEH) with a two-degree-of-freedom (2DOF) structure to work in two vibration modes for broadband operation. The PMEH is fabricated by bonding a piezoelectric ceramic lead zirconate titanate Pb(Zr,Ti)O3 (PZT) to phosphor bronze, which can work in a high-acceleration ambient with good durability. The maximum open-circuit voltage and output power of the PMEH are 23.6 V and 64.69 μW at the first resonant frequency of 27.4 Hz when the input vibration acceleration is 2 g (9.8 m/s2), while they are 14 V and 56.75 μW at the second resonant frequency of 93.4 Hz when the input vibration acceleration is 8 g, respectively. The fabricated PMEH scavenged the vibration energy of a vacuum compression pump and an ultrasonic cleaner and generated maximum output powers of 10.45 and 16.59 μW, respectively. The experimental results show that the device has good environmental adaptability.