In this study, we propose a passive air sampler (PAS) that mainly consists of activated charcoal sorbent, a radial diffusive body, and a protective shield for the outdoor monitoring of volatile organic compounds (VOCs). Due to its reusable accessories and small size, this PAS is cost-effective and highly convenient for outdoor deployment. The estimated sampling rates (SRs) for 28 VOCs were very close to the theoretical values over a 6-month field test. We evaluated the performance of the PAS with benzene, toluene, ethylbenzene, and xylenes (BTEX) and determined the method detection limits (MDLs) (0.02–0.04 µg m–3), recovery values (95.3 ± 9.8–99.8 ± 7.5%), repeatability (3.2 ± 2.2–4.6 ± 2.9%), and uncertainties (10.1 ± 3.8–12.9 ± 4.5%), which are comparable to those of previously reported samplers and meet the requirements of European Standards (EN) 13528. The deployment times for obtaining reliable time-weighted average (TWA) atmospheric concentrations of BTEX ranged from 2 days to a minimum of 3 months according to corresponding background concentrations in the ambient air. Moreover, the atmospheric concentrations of BTEX measured by the sampler in this study compared favorably with values from both active and passive sampling methods, with R2 ≥ 0.97 (p < 0.0001). Finally, a 12-month field test was performed after evaluating the sampler, and the results showed apparent seasonal variations of atmospheric VOC concentrations, which were dominated by the sampling location and wind direction.