Purpose Educating patients to self-manage chronic diseases such as asthma is a key role for nurses. The success of this education is often limited by low patient self-efficacy. In this study, we hypothesized that the self-efficacy of patients could be enhanced if their education was based on biofeedback of their own self-management, following a nurse led educational intervention. Patients and Methods Patients with severe and uncontrolled asthma from one centre who participated in an eight-month, nurse-led asthma education and dose adjustment Randomised Control Trial (RCT) were studied (NCT02307669). Inhaler adherence and technique of use were objectively assessed using a validated digital device. The data recorded on this device was used as the basis for the individualised biofeedback. The Asthma Self-efficacy Questionnaire was used to assess self-efficacy. Results A total of 88 participants (44 in each group) completed the asthma self-efficacy questionnaire at the end of the study. The mean overall level of self-efficacy was high across both groups; 91 (8.7), with both biofeedback and standard care groups having similarly high levels of self-efficacy, biofeedback group: 89 (10) and standard care group 93 (6). Self-efficacy was not related to objective measures of adherence at either the start of the study, 68 (26), p =0.23, or the end of the study, 58 (32), p =0.62. It was also not related to peak expiratory flow (PEF) at the end of the study in either group (r2= 0.0245, p =0.14). Self-efficacy was related to asthma control test (ACT), 18 (5.5), p =0.0014 and quality-of-life measures; EuroQol (EQ5D3L) 6.4 (1.5) p =0.02. Conclusion Repeated nurse-delivered education results in high levels of self-efficacy among patients with severe asthma. A high level of perceived self-efficacy should not be assumed to result in higher inhaler adherence.