Background: This study evaluated whether providing intensive home treatment (IHT) to patients experiencing a psychiatric crisis has more effect on self-efficacy when compared to care as usual (CAU). Self-efficacy is a psychological concept closely related to one of the aims of IHT. Additionally, differential effects on self-efficacy among patients with different mental disorders and associations between self-efficacy and symptomatic recovery or quality of life were examined. Methods: Data stem from a Zelen double consent randomised controlled trial (RCT), which assesses the effects of IHT compared to CAU on patients who experienced a psychiatric crisis. Data were collected at baseline, 6 and 26 weeks follow-up. Self-efficacy was measured using the Mental Health Confidence Scale. The 5-dimensional EuroQol instrument and the Brief Psychiatric Rating Scale (BPRS) were used to measure quality of life and symptomatic recovery, respectively. We used linear mixed modelling to estimate the associations with self-efficacy. Results: Data of 142 participants were used. Overall, no difference between IHT and CAU was found with respect to self-efficacy (B = − 0.08, SE = 0.15, p = 0.57), and self-efficacy did not change over the period of 26 weeks (B = − 0.01, SE = 0.12, t (103.95) = − 0.06, p = 0.95). However, differential effects on self-efficacy over time were found for patients with different mental disorders (F(8, 219.33) = 3.75, p < 0.001). Additionally, self-efficacy was strongly associated with symptomatic recovery (total BPRS B = − 0.10, SE = 0.02, p < 0.00) and quality of life (B = 0.14, SE = 0.01, p < 0.001). Conclusions: Although self-efficacy was associated with symptomatic recovery and quality of life, IHT does not have a supplementary effect on self-efficacy when compared to CAU. This result raises the question whether, and how, crisis care could be adapted to enhance self-efficacy, keeping in mind the development of self-efficacy in depressive, bipolar, personality, and schizophrenia spectrum and other psychotic disorders. The findings should be considered with some caution. This study lacked sufficient power to test small changes in self-efficacy and some mental disorders had a small sample size. Trial registration This trial is registered at Trialregister.nl, number NL6020.