Cystic Fibrosis (CF) is a progressive condition resulting in reduced lung function and strongly associated with elevated anxiety and depression symptoms. Self-concept refers to an individual's overarching sense of identity, a positive level of which is widely associated with reduced anxiety and depression. There is a significant lack of self-concept research within CF. This study explores the association between self-concept and anxiety and depression in adults with CF. 64 adults living with CF in Western Australia completed validated online questionnaires (Generalised Anxiety Disorder-7, Patient Health Questionnaire-9, Tennessee Self-Concept Questionnaire 2: Short-Form) and consented to the collection of medical data. Descriptive, t-test, correlation and multiple regression analysis were undertaken. Higher levels of self-concept were associated with lower levels of anxiety and depression symptoms. Lower self-concept levels were a significant predictor of increased anxiety and depression symptoms after accounting for physical health status. Mean self-concept scores for those who required mental health intervention were significantly lower compared to those that did not. This study identifies a significant relationship between self-concept and anxiety and depression in adults with CF. Further research is required to establish causation and test the feasibility of self-concept interventions in reducing anxiety and depression symptoms.