Constructed wetlands (CWs) are increasingly recognized as an environmentally friendly and economically viable approach to wastewater management. These systems integrate ecological principles with engineered layouts, enabling efficient treatment through the combined action of plants, substrate, and diverse microbial populations. Such interactions play a crucial role in reducing organic pollutants, excess nutrients, heavy metals, and even newly emerging contaminants. However, evaluating CWs solely on their treatment efficiency provides only a partial understanding of their overall performance. For long-term adoption and sustainability, it is essential to consider environmental, economic, and social dimensions together. Life Cycle Assessment (LCA) serves as a valuable tool in this regard, as it examines impacts throughout the entire lifespan of the system from construction and operation to final closure or repurposing. By incorporating LCA into CW planning, it becomes possible to identify trade-offs between treatment benefits and resource demands, while also exploring ways to minimize energy use, land requirements, and greenhouse gas emissions. This chapter highlights the functioning of constructed wetlands as a wastewater treatment strategy, outlining their design principles, operational aspects, and performance outcomes. Special attention is given to the role of LCA in strengthening the sustainability perspective of CWs. By linking technical efficiency with broader sustainability indicators, the chapter emphasizes the relevance of CWs as a decentralized treatment option that supports global objectives of environmental stewardship and sustainable resource use.