Background: Hypertension (HT) is a global health problem. Although there are effective treatment protocols, patients have difficulty in adapting to regular use of drugs, diet, and lifestyle changes. Mobile apps can be a potential alternative for managing HT and improving self-care behavior. Purpose: This study aimed to determine the effect of mobile application follow-up on treatment compliance and self-care management in patients with HT. Methods: This randomized controlled trial was conducted in November 2021 and March 2022 with 40 experimental and 40 control group patients with HT. Research data were collected using a patient information form, “Hill-Bone Hypertension Treatment Compliance Scale (HBHTTCS),” “Hypertension Self-Care Profile-Motivation Scale (HTSPMS),” a mobile application program (daily blood pressure, pulse, medication, diet, exercise tracking) uploaded to the mobile phones of the patients, and individual motivational messages. Results: The mean total score of the HBHTTCS at Week 6 was 14.57 ± 1.89 and the mean total score of the HTSPMS was 78.15 ± 2.05. There was a statistically significant difference in mean total HTSPMS (p = 0.000) and HBHTTCS (p = 0.000) scores and mean scores on medical (p = 0.002) and nutrition (p = 0.002) subscales of HBHTTCS between the first interview (1st-week follow-up) and the last interview (6th-week follow-up) of patients in the intervention group. Conclusions: This study showed that mobile application follow-up increased motivation levels and treatment compliance in patients with HT and resulted in better self-care. These positive findings indicate importance of integrating mobile applications in the disease management of HT patients. Trial Registration: ClinicalTrials.gov ID: NCT05334446, https://clinicaltrials.gov/ct2/show/NCT05334446.