Traditional textile bleaching techniques need to be given another look in light of the environment and lifestyle of today. To achieve higher whiteness values while using less water and chemicals during the bleaching process, it is crucial for both the environment and the economy. The most effective disinfectant, chlorine dioxide (ClO2), is produced by sodium chlorite (NaClO2), which is a suitable oxidant for the job. During the COVID-19 pandemic, NaClO2 gained popularity and became more widely available. The use of NaClO2 as a bleaching agent offers many benefits, including a decrease in the number of washing steps and an increase in cotton strength. This reagent's ability to produce less weight loss in the fabric than other reagents is another benefit. Therefore, the present work was intended to improve the process conditions (different temperatures, concentrations, and times) of bleaching of cotton fabric by using NaClO2.A high whiteness index (W.I. = 88) was obtained by utilizing phosphonic acid (HEDP), and the ideal temperature and duration were found to be 30 min at 65 °C and 30 min at 85 °C. Moreover, the tensile strength, weight loss and morphologies of the samples were examined. Because sodium chlorite does not leave behind any alkaline residues, it has been found to do less harm to cotton fibers and use less water for rinsing.