Blood pressure (BP) naturally undergoes fluctuations and variations, particularly during anesthesia administration during surgery, hemodialysis, upper and lower gastrointestinal endoscopy, exercise testing, arterial and venous catheterization, and rehabilitation. These changes in BP may lead to life-threatening events. The performance of the Omron HBP-M4500 device in monitoring blood pressure (BP) in the upper arm was validated according to the International Organization for Standardization (ISO) 81060-2:2018+amendment (Amd) 1:2020 protocol. The device was used to assess 113 participants in the inflation mode, and 107 participants in the deflation mode. All the patients fulfilled the inclusion criteria, including the arm circumference range and systolic and diastolic BP levels, outlined in the protocol. Data validation and analysis were performed according to the manufacturer's instructions. In criterion 1, the mean ± standard deviation (SD) values of the differences between the test device and reference BP were -0.6 ± 5.80/2.8 ± 6.78 mmHg (systolic/diastolic) and -1.0 ± 5.35/3.2 ± 6.52 mmHg for the inflation and deflation modes, respectively. These data fulfilled the ISO81060-2:2018+Amd1:2020 requirements of ⩽ 5 ±⩽ 8 mmHg. In criterion 2, the differences were -0.6 ± 4.44/2.8 ± 6.26 and -1.0 ± 3.84/3.2 ± 6.09 mmHg for the inflation and deflation modes, respectively, fulfilling criterion 2 with SD values of ⩽ 6.91 and ⩽ 6.87 for systolic BP and ⩽ 6.34 and ⩽ 6.14 for diastolic BP in the inflation and deflation modes, respectively. These two criteria were fulfilled in both studies. The Omron HBP-M4500 device, either in inflation or deflation mode, fulfilled the criteria outlined in the ISO protocol. Therefore, this device is valuable for BP measurement in clinical and hospital settings.