An activated carbon fiber (ACF) has been developed for use as an extraction fiber in solid-phase microextraction (SPME) and used to determine benzyl chloride, benzyl dichloride, and benzyl trichloride in water samples by headspace (HS) analysis. Experiments showed that ACF has excellent adsorption capacity. Its well-distributed surface makes desorption swift in a GC–MS injector. Several conditions affecting the ACF-SPME procedure, for example adsorption mode, adsorption time and temperature, and desorption time, were optimized. The optimized HS-ACF-SPME method has acceptable linearity, good precision, and reasonable RSD values for the compounds studied. The ACF is, therefore, a promising alternative for SPME.