The importance of sustainability in textiles increases day by day. The reuse, recycle, and upcycle of materials are popular techniques of sustainability. Managing waste of production is as important as finding new raw material sources for production. Pineapple is a delicious and preferred fruit, and disposing the leaves of pineapple from the field is also a big problem for farmers. Transforming this waste into a value-added product is quite important but also difficult. This study is about the optimum yarn linear density and blend type for pineapple leaf as a fiber. During the study, pineapple leaf was added to viscose and cotton, and ring-spun yarns were produced with different counts. According to the quality parameters, the most convenient linear density for each blend is selected, and then knitted fabrics are produced by these yarns. The dyeing process is applied to detect the thermal performances of samples. Finally, the best yarn type and blend type are chosen in accordance with all dependent values.