Due to the continuous optimization of cutting plans, the cotton scrap size resulting from the cutting of components for clothing production (post-industrial residues) is often considered insufficient to obtain fibres with the proper length to produce a new yarn through mechanical recycling processes; so it is important to search for other applications for these wastes. In this context, small pieces of cotton were submitted to a shredding process to obtain recycled fibres. Cotton small pieces and recycled fibres were then submitted to a refining process to achieve refined fibres. Using these materials alone and in blends with refined and unrefined bleached eucalyptus kraft pulp (BEKP), wet-laid nonwovens were developed and characterized. An analysis of the results revealed that the replacement of unrefined BEKP by 70% cotton waste fibres in wet-laid nonwovens, reducing the use of virgin raw material, enhances the structures’ mechanical properties by 80% and 14%, for small pieces or recycled fibres, respectively. Additionally, refining small pieces of cotton seems to be more promising than refining recycled fibres, because less steps are required to obtain wet-laid nonwovens with better mechanical properties. These results highlight the potential of this approach to be explored further for different products and end applications.