Activated carbon fibers (ACFs) have emerged as promising adsorbents for environmental applications in the removal, separation, and modification of organic compounds in liquid and gas phases. Recent research has focused on enhancing the effectiveness of ACFs via precursor and surface modification, aiming to enhance their affinity for specific pollutants. Hence, the present review reports recent research advances in this area, focusing on ACF production and modification techniques, along with their respective advantages and disadvantages. After a brief description of ACFs, their state-of-the-art surface modification techniques are systematically summarized, divided into two categories: (i) type of precursor [e.g., polyacrylonitrile (PAN), pitch, phenolic resin (e.g., novoloid), biomass] and (ii) type of surface modification (wet or dry). In short, this review presents recent advances in the preparation and modification of ACFs for the removal of organic compounds from aqueous and gas phases; various fabrication techniques and the adsorption mechanisms of organic compounds are also discussed in detail.