The world in which we live is changing at a much faster and more uncontrolled rate. This situation brings with it both negative and positive changes. The textile industry is also part of this rapid change. The growth of the world’s population and the alterations in consumer habits that this change has brought with it also affect the textile industry. In particular, polluting dyehouses and the synthetic dyes used in them are harming the world. This situation is unsustainable. For this reason, the use of natural dyes instead of synthetic dyes in the coloring of textile products is increasing rapidly. In this study, a blend of 80% cotton and 20% wool was dyed with cinnamon, and its fastness and mechanical performance were tested. In addition, the dyeing results were analyzed using a spectral method, FTIR, and SEM. In this study, natural fiber blends with two different chemical structures were dyed with cinnamon in one bath. The fastness values obtained as a result of the dyeing process were very good. The grey scale value of saliva fastness determined through evaluation was 5. The observed strength increase of approximately 24% in the yarn after dyeing was also remarkable. In conclusion, environmentally friendly dyeing was carried out in this study, and a contribution was made to a sustainable world.