Chronic diseases have emerged as a significant threat to global health, with their persistence and prevalence presenting substantial challenges for both patients and healthcare systems. Traditional healthcare often struggles to address the long-term, continuous monitoring and therapy needs of individuals with chronic conditions. Smart textiles represent one of the innovative wearable medical monitoring technologies that integrate bioelectronics with textile processes, offering a comfortable and portable platform for health monitoring and therapy. These smart textiles continuously gather various physiological signals related to health and can deliver personalized therapy. Such textile-based, wearable, and unobtrusive monitoring and therapy devices are essential for enhancing the quality of life for patients with chronic diseases, improving their self-care capabilities, and increasing their comfort. This review provides an in-depth exploration of the application of smart textiles in the precision diagnosis and treatment of chronic diseases, covering their manufacturing technologies, long-term monitoring, physiological state assessment, rehabilitation therapy, and their interconnectivity with IoT and 5 G technologies. Finally, we summarize the prospects and challenges associated with the commercialization of these technologies, aiming to deliver more efficient and precise healthcare services to patients with chronic diseases.