<p>Functionalizing carbon materials with heteroatoms such as oxygen, nitrogen, and sulphur is widely reported as an effective strategy for tailoring surface chemistry and enhancing performance in many applications. The incorporation of these functional groups can significantly modify the surface polarity, acidity/basicity, hydrophilicity, and electronic characteristics of carbon materials, making them more interactive with reactive species and pollutants. This review provides a comprehensive and integrated overview of the major strategies to introduce oxygen-, nitrogen-, and sulphur-containing functionalities onto carbon surfaces including chemical, thermal, plasma, and precursor-based methods. Emphasis is placed on the nature, stability and chemical behaviour of the resulting surface functionalities and their possible influence on the adsorption capacity, catalytic activity, and electrochemical performance. While extensive studies exist on individual heteroatoms, their comparative effects, formation pathways, and structure-property relationships remain fragmented in the literature. By consolidating dispersed findings, this review clarifies how heteroatom functionalization governs carbon surface reactivity and identifies key knowledge gaps related to functional group stability under realistic operating conditions. The presented insights aim to inform the rational design of heteroatom-modified carbon materials, particularly for environmental and sustainable technologies.</p>