Background: Living with a chronic disease such as Diabetes Mellitus (DM) could be challenging since it is highly demanding due to the need for daily management and intensive kind of care. So, this study aimed to assess Jordanian diabetic adolescent self-care, knowledge, and evaluate the impact of psychological well-being. Methods: A quantitative cross-sectional design was used in this study. The study participants, (n=400) where a convenience sampling method used, were selected from a number of Jordanian Ministry of Health hospitals and data was collected between December 2019 to January 2021. Self-administered questionnaire comprised of four major sections was used. The first section measured the patients sociodemographic, family educational and economic characteristics of the patients along with their past medical history and clinical test like the (Hba1c) glycated hemoglobin. Section-II measured the patients' knowledge of diabetes and pharmacotherapy. Section-III measured the children's perceived level of diabetic self-care, and section-IV measured the level of psychological well-being of diabetic children. Results: The study found that adolescents are moderately aware of their illness but had poor knowledge about the treatment. It was found that there is a significant but weak correlation between both, adolescent's knowledge about diabetes and its management and psychological well-being, and diabetes self-management (r=0.255, p<0.01; r=0.125, p<0.05; and r=0.112, p<0.05, respectively). The patient's knowledge about diabetes mellitus disease was a predictor of good diabetic self-care (p<0.001). Conclusion: Establish educational sessions about diabetes disease for children with type 1 DM is essential to ensure good self-management activities