Aramid fabrics were photo-oxidised by ultraviolet/ozone irradiation. The surface properties of the modified fabrics were characterised by reflectance, attenuated total reflectance, electron spectroscopy for chemical analysis and surface zeta potential. The ultraviolet irradiation caused the oxygen content of the aramid fabric surface to increase, with the appearance of carbonyl and hydroxyl groups, and reduced the surface zeta potential, coupled with improved water wettability. Moreover, the crystalline structure did not change after ultraviolet/ozone treatment according to X-ray diffraction results. The modified aramid fabrics showed higher affinity to cationic dyes, which may have resulted from the newly introduced electrostatic interaction between cationic dyes and anionic dyeing sites on the photo-oxidised surface layers. Although colour fastness to both staining and rubbing were good to excellent, colour fastness to shade change was moderate. Furthermore, the ultraviolet/ozone pretreatment and cationic dyeing of aramid fabrics may overcome the loss in the mechanical properties associated with previously recommended dyeing methods for aramid fabrics.