In response to the narrow working-frequency band and single-directional vibration capture of linear and single-mode vibration-energy harvesters, this paper proposes a novel multi-directional vibration-energy harvester that aims to enhance the capture of vibration energy in the environment. This device combines piezoelectric and electromagnetic energy harvesters. It effectively captures multi-directional vibrations through a spiral cylindrical spring and top mass and transfers the vibration energy to a piezoelectric beam through magnetic force. The spring-mass structure is designed to support multiple vibration modes at a lower frequency range, broadening the resonance-frequency band of the energy harvester. To fully utilize the piezoelectric material, the device implements a variable-width piezoelectric cantilever beam, ensuring a uniform stress distribution. The permanent magnet at the free end of the piezoelectric beam generates a changing magnetic field in response to the beam vibration, inducing a voltage in the coil. Through finite-element analysis and experimental testing, the composite energy harvester was verified to capture multi-directional vibration energy. Moreover, the maximum output power of the piezoelectric, electromagnetic, and composite energy harvesters under z-directional vibration excitation was tested. The composite energy harvester yields an output power of 3.276 mW when subjected to a 9.5 Hz sine-wave excitation with a 2 mm z-axis amplitude. This system offers continuous power for low-power sensors, thus providing technological support for mechanical energy harvesting and energy conversion.