BACKGROUND High blood pressure (BP) is the single largest contributor to mortality world-wide. AIM To investigate the effectiveness of a pharmacists-led intervention to improve BP control using automated office blood pressure (AOBP). METHOD In this prospective parallel group, unblinded, cluster-randomised trial, 54 pharmacies enrolled pre-treated patients with uncontrolled AOBP above 135/85 mmHg. In the interventional group, pharmacists referred patients to the treating physician for therapy intensification in a structured fashion. In the control group, AOBP was recorded until the end of the trial. The primary endpoint was the proportion of patients achieving BP control at the threshold of 135/85 mmHg after 10 weeks. Key secondary endpoints were systolic AOBP reductions after 10 and 20 weeks. RESULTS A total of 497 patients were included between 2017 and 2019. In the interventional and control group, 61.5% and 19.8% of patients underwent a therapy modification within 20 weeks. The primary endpoint was achieved in 38.8% in the interventional group and 31.2% in the control group (mean difference 7.6%, 95% CI -8.1; 23.3, p = 0.336). Mean systolic AOBP reductions were greater in the interventional vs. control group at 10 and 20 weeks (14.3 ± 7.4 vs. 6.9 ± 7.0 mmHg, mean difference 7.3 mmHg, 95% CI 3.2;11.5, p