Due to the electro-optic property of InGaN multiple quantum wells, a III-nitride diode can provide light transmission, photo detection, and energy harvesting under different bias conditions. Made of III-nitride diodes arrayed in a single chip, the combination allows the diodes to transmit, detect, and harvest visible light at the same time. Here, we monolithically integrate a III-nitride transmitter, receiver, and energy harvester using a compatible foundry process. By adopting a bottom SiO2/TiO2 distributed Bragg reflector, we present a III-nitride diode with a peak external quantum efficiency of 50.65% at a forward voltage of 2.6 V for light emission, a power conversion efficiency of 6.68% for energy harvesting, and a peak external quantum efficiency of 50.9% at a wavelength of 388 nm for photon detection. The energy harvester generates electricity from ambient light to directly turn the transmitter on. By integrating a circuit, the electrical signals generated by the receiver pulse the emitted light to relay information. The multifunctioning system can continuously operate without an external power supply. Our work opens up a promising approach to develop multicomponent systems with new interactive functions and multitasking devices, due to III-nitride diode arrays that can simultaneously transmit, detect, and harvest light.