Background: High blood pressure (BP) prevalence is high and increasing in many low- and middle-income countries (LMICs). Unfortunately, uncontrolled BP causes cardiovascular diseases (CVDs) and kidney disease. The high morbidity and mortality that results from uncontrolled BP comes at a high cost to families and countries. Knowledge of the barriers to BP control may help in crafting suitable interventions. Methods: This was a descriptive qualitative study to explore the barriers to BP control among patients already on BP treatment in public PHC clinics in Gaborone Botswana. Data was collected from patients, nurses, doctors, and district health managers, through structured interviews. The interviews were conducted using an interview guide, and they were audio recorded. The interviews were translated into English transcripts and the transcripts were analysed for themes using NVivo. Results: Eighteen participants were interviewed. The barriers to BP control were health system related, healthcare worker related, patient related, and socio-economic. Conclusions: Barriers to BP control among patients receiving BP treatment were multifactorial and included health system, healthcare worker, patient, and socioeconomic factors. There needs to be a holistic approach to overcome these barriers and special attention to be given to doctor knowledge, patients’ lifestyles, and adherence to treatment.