New techniques and materials are called for wastewater treatment due to the shortage of worldwide fresh water and the increasing water demand. As a simple and efficient method, adsorption technique has been extensively applied to remove organic and inorganic pollutants from contaminated water. The application of carbon nanomaterials, such as activated carbon, carbon nanotubes (CNTs), graphenes and their derivatives/analogues, in wastewater treatment has also been investigated due to their unique properties, such as wide availability, porous structure, large surface area, tunable morphology and nontoxicity. This review highlights the recent advances of wastewater treatment utilizing carbon nanomaterial modified composites as adsorbents. The adsorption phenomenon and its mechanism are briefly discussed. Detailed discussions are focused on the selective adsorption of carbon nanomaterial composites to unique pollutants. The remaining challenges are also mentioned.