Self-care is one of the basic principles in the management of chronic diseases, which influences follow-up and adherence to treatment. Therefore, the current study was conducted with the aim of comparing the effect of teach-back (TB) and a smartphone application on adherence to treatment in patients with inflammatory bowel disease (IBD). The current clinical trial was conducted among 80 patients with IBD in Mashhad, Iran, in 2021-2022. Self-care education (diet, personal and social relationships, medications, sleep, physical activity, sexual relationships, etc.) was provided through TB method in one group and by using a smartphone application in another group. The control group only received the routine education. A checklist for demographic information and the adherence questionnaire in patients with chronic diseases were used for data collection. Patients' mean age was 38.73 ± 10.32 years. The majority of patients had ulcerative colitis (81%) and were married (67%). Mean and standard deviation score of adherence to treatment were the same in all three groups before the intervention (P = 0.668). The mean post-test scores of adherence to treatment in the TB, application, and control groups were 170.04 ± 14.19, 167.99 ± 11.59, and 159.60 ± 10.94, respectively. The difference was statistically significant (P = 0.003). A significant difference was observed in regards to the mean post-test scores of adherence to treatment between TB and control groups (P = 0.004) and app and control groups (P = 0.048). However, the difference between TB and app groups was not significant (P = 0.989). TB method and smartphone application have the same effect on adherence to treatment in patients with IBD. Due to the usability and cost-effectiveness of smartphone applications, this method can be used by health-care providers to educate this group of patients.