In this paper, we report the real-time, ultrasensitive, reproducible detection of volatile odorant molecules emitted by human based on free-standing silicon nanowire (SiNW) array functionalized with Anopheles gambiae odorant binding protein (AgOBP). Highly responsive SiNW array was fabricated with a novel low-cost top-down fabrication approach. The free-standing and triangular cross sectional structure allowed efficient sensing of AgOBP conformational change induced by odorant binding. The resulting bioelectronic nose (B-nose) possessed high sensitivity down to several ppb, and outstanding size and functional group selectivity. The device showed reproducible and long-lasting performances. We also demonstrated the multiplex detection of various odorants with a sensor array functionalized with three different AgOBPs. The AgOBP-SiNW B-nose reported herein provides a powerful and effective platform for future development of multiplexed human body odor sensor arrays.