In this study, we synthesized multifunctional ZnO nanorod using Allium bourgeaui subsp. bourgeaui extract and characterized it via FTIR, XRD, UV–Vis, and SEM. The average length of ZnO nanorods was 264.881 nm. The hexagonal wurtzite structure was confirmed by XRD, and the band gap was found to be 3.02 eV. Bioactive phytochemical components in the Allium bourgeaui subsp. bourgeaui extract were discovered using gas chromatography/mass spectrometry (GC/MS) and FTIR analyses. ZnO was applied as interlayer in photodiode structure and was also analyzed as self-powered photodetector under various wavelengths. The rise time and fall time of the ZnO interlayered diode were investigated at 100–1000 kHz using a home-made apparatus containing an STM-based pulse generator and a signal amplifier integrated with an oscilloscope. Moreover, ZnO was also used as photocatalyst to degrade methylene blue. The degrading efficiency was 92.38% in 120 min under UV. In addition, ZnO showed antibacterial properties against E. coli, P. aeruginosa, and S. aureus bacteria. Herein, this study shows a facile and environmentally friendly synthesis of ZnO nanorods with comprehensive applications of ZnO in various fields.