Abstract Global textile consumption has increased significantly in the last decades and, consequently, millions of tons of textile waste have been discarded every year. Landfills and incinerators are their main fates, causing several and significant environmental problems. Cotton, second to polyester, is the most widely used fibre in the textile industry. Therefore, the recovery of this fibre from wastes is an imperative waste management strategy to mitigate the environmental impacts related with their disposable as well as its farming. Various approaches have been employed to reuse these waste cotton textiles. The extraction of cellulose nanomaterials, such as cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) from these solid wastes has shown to be a promising methodology. Owing to its outstanding and natural properties, nanocellulose applications have gained high attraction in different areas. In this review, the potential of using waste cotton textiles to extract nanocellulose instead of other cellulosic resources is highlighted and discussed. The concept of nanocellulose and the differences between types is well clarified. A background on the typically applied extraction methods is presented, giving special relevance to those already employed to extract nanocellulose from textile wastes, in particular those containing cotton. In addition, limitations to these methodologies are also examined, as well as possible applications of the extracted nanocellulose on high value-added products.