Activated carbon fiber (ACF) is widely used as a critical adsorbent for removing gaseous radioiodine produced during spent fuel reprocessing. However, conventional ACF exhibits a broad pore distribution and high moisture affinity, significantly diminishing their effectiveness in capturing iodine under humid conditions. In this study, we endowed bare ACF with the dual functions of preferentially I2-matched pores (93.62 % microporosity) and hydrophobicity (water contact angle of 132.1°) using a facile method of depositing polydivinylbenzene (PDVB) nanoparticles, overcoming the limitations of traditional modification methods that have a single target. We successfully prepared amine-functionalized hydrophobic ACF (ACF-PDA@PDVB-HMTA) with a high specific surface area (1392 m2/g) by introducing iodine-affinity reactive groups (NH2, CN, and OH). ACF-PDA@PDVB-HMTA exhibited a groundbreaking static adsorption capacity of 1886 ± 56 mg/g for I2 at 96 % relative humidity. Notably, its dynamic iodine adsorption on iodine-water vapor mixed stream was 1873.78 mg/g, which is 66.31 % higher than that of the original ACF (1126.7 mg/g) at real-life conditions of 75 °C and 50 % relative humidity, underscoring the synergistic “1 + 1 + 1 = 3” effect of the three mechanisms. The scalable application of the spray-deposited PDVB approach to other porous carbon materials also yielded exemplary modification results. This synergistic strategy provides a promising solution for improving the overall I2 capture.