Ambient vibration energy harvesting technology can provide green self-powered supply technology for low-power electronic devices in the Internet of Things (IoTs). In response to the shortcomings of traditional linear cantilever beam energy harvesters with high natural frequencies and low energy capture efficiency, a tuning fork-shaped cantilever beam structure is proposed to collect vibration energy in the environment. This overcomes the disadvantage of traditional cantilever beam structures, where the free end section, due to its small strain during vibration, is not conducive to energy collection. As a result, the energy harvesting efficiency of the system is significantly enhanced. The Lagrange equation is used to establish the dynamic equation of a tuning fork piezoelectric cantilever beam under harmonic excitation. The influence of structure size, added tip-mass and load resistance on the energy capture characteristics of the system are analyzed through a combination of the theoretical analysis, finite element simulation (FEM) and experimental results. The results show that introducing a bifurcation structure at the free end of the cantilever beam can reduce the fundamental frequency of the system, proving that the tuning fork piezoelectric cantilever beam energy harvester is more conducive to low-frequency ambient vibration energy harvesting. When the acceleration excitation amplitude is 0.5 m/s², the peak output power of the system is 7 mW. Further optimization of the structure by adding a 20 g tip-mass at the free end increases the peak energy capture output power to 18 mW. Design a piezoelectric energy capture interface circuit to collect and convert electrical energy directly to power LED lights (light emitting diodes). Experimental results can simultaneously light up 50 LED lights. The research results can provide theoretical support for energy collection in low-frequency vibration environments and for achieving self-powered design of low-power IoT sensors below 80 Hz.