We report on the demonstration of a 386 nm light emission and detection dual-functioning device based on nonpolar a-plane n-ZnO∕i-ZnO∕p-Al 0.1 Ga 0.9 N heterojunction under both forward and reverse bias. The electroluminescence intensity under reverse bias is significantly stronger than that under forward bias, facilitated by carrier tunneling when the valence band of p-AlGaN aligns with the conduction band of i-ZnO under reverse bias. Also amid reverse bias, the photodetection was observed and applied in a duplex optical communication device. Optical polarization of the light emission is studied for potential polarization-sensitive device applications. The proposed device provides an important pathway for the multifunctional devices operating in a UV spectrum.