Pure water and clean air are the most fundamental necessities of life. The demand for safe drinking water and fresh air is high in many regions worldwide. The scarcity of these resources is mainly driven by population growth, which leads to pollution and environmental issues like droughts and poor air quality. Carbon nanomaterials are being utilized in a wide range of applications, and their unique properties make them ideal for ecological solutions, such as water purification, heavy metal removal, and gas separation. Advancements in membrane synthesis, a cutting-edge area of nanotechnology research, have resulted in both natural and synthetic membranes. This discussion highlights the exceptional potential of carbon-based nanomaterials, such as graphene, carbon nanotubes (CNTs), and their derivatives, which have been highly favored since their discovery. Graphene and CNTs are being extensively studied for environmental applications like filtration and adsorption, demonstrating remarkable efficiency in removing contaminants, such as organic matter, heavy metal ions, bacteria, and particulate matter (PMs). The separation mechanisms employed by carbon-based nanomaterials largely depend on Van der Waals forces and π–π interactions. Moreover, the functionalization of carbon nanomaterials can enhance molecular interactions, such as hydrogen bonding and chelation, further improving separation and filtration efficiency. Functionalized carbon nanomaterials also offer selective separation capabilities, making them even more effective in environmental applications.