Background <p>Despite the increase in antiretroviral treatment availability, missed clinic appointments continue to pose a challenge in managing People living with HIV/AIDS (PLWHA). This study aimed to assess the impact of M-health in keeping clinic appointments among PLWHA.</p> Methods <p>This quasi-experimental study encompassed all PLWHA who received care at the Federal University Teaching Hospital Owerri (FUTH) and the Imo State Specialist Hospital (ISSH) Umugumma, specifically targeting those who had missed their clinic appointments for duration of 180 days or more since their last visit. The total comprises 223 individuals from FUTH and 411 individuals from ISSH. The study was conducted over a period of six months and included both an intervention group and a control group. The intervention group received a two-way text message three times per week, in addition to a weekly phone call, whereas the control group received only the standard care, which did not include any text message reminders throughout the duration of the study. Data analysis involved the use of independent sample T-tests, Chi-square tests, and bi-variable logistic regression. Statistical significance was evaluated using the odds ratio, employing a 95% confidence interval and a p-value threshold of less than 0.05.</p> Results <p>The study revealed a significant difference in appointment adherence between the intervention group and the control group. The p-values from the t-test indicated that age, income, and duration on ART among the participants in the two hospitals were not statistically significant (<i>p</i> = 0.170, 0.510, and 0.318, respectively). The chi-square test analysis of the participants’ socio-demographic characteristics in the two hospitals showed that education, marital status, and occupation were significant (<i>p</i> &lt; 0.0001), while gender was not significant. Additionally, the regression analysis conducted after the intervention indicated that m-health increased clinic appointment attendance among participants in the test group (<i>p</i> &lt; 0.0001).</p> Conclusion <p>This research study provides evidence that the implementation of phone call and text message reminders led to a significant decrease in missed appointment rates within the intervention group. The mobile health intervention significantly improved the promptness of clinic appointments among participants. Hospital management and HIV programme directors should consider incorporating mobile health into the standard care of PLWHA.</p> Clinical trial number <p>Not applicable.</p>