Obesity and hypertension are one of the most important cardiovascular risk factors. It is predicted that by 2030 almost two-thirds of the global population will struggle with being overweight or obese. Ambulatory Blood Pressure Measurement (ABPM) is a tool for a detailed analysis of mean blood pressure values and assessing the blood pressure profile during the night with the daily values and optimal treatment determination. The study aimed to assess the frequency of hypertension in patients with pathological obesity. The study consisted of two groups depending on their Body Mass Index (BMI): Group 1 BMI > 25 kg/m2; < 40 kg/m2; Group 2 (243 overweight and obese patients): BMI ≥ 40 kg/m2. Each patient was carefully interviewed, considering their use of the antihypertensive drugs. Each patient was subject to the ABPM assessment. Arterial hypertension (HT) was diagnosed at arterial blood pressure (BP) values > 135/85 mmHg based on the European Society of Hypertension (ESH) test bench. Depending on the patient’s history, ABPM, and in-office BP measurements, patients were diagnosed with HT treated, newly diagnosed, or without HT. Based on the in-office BP and ABPM measurements taken, the diagnosis of white-coat uncontrolled hypertension (WUCH) and masked uncontrolled hypertension (MUCH) was diagnosed. The analysis of parameters revealed that all BP values were significantly higher in group 2. More than half of the patients in both groups had been previously treated for HT. Based on ABPM, newly diagnosed HT was identified significantly more often in patients with higher BMI. The younger individuals were significantly more likely to have WUCH.