Hypertension is a major risk of cardiovascular diseases. This study’s aim was to examine associations between hypertension and a priori known lifestyle risk factors, including weight status and Mediterranean diet adherence. The study included a representative sample of the adult population (N = 3775 (40.8% males)), from the Hellenic National Nutrition and Health Survey (HNNHS), which took place from September 2013 to May 2015. Demographic and anthropometric data were collected using validated questionnaires, and blood pressure (BP) measurements were performed for the two main metropolitan areas (N = 1040; 41.1%). Hypertension diagnosis was according to the International Classification of Diseases (ICD-10) guidelines. Weighted proportions, extended Mantel–Haenszel (M–H) analyses, and multiple logistic regressions (for the survey data) were performed. Mean systolic BP (SBP) and diastolic BP (DBP) were 118.6 mmHg and 72.2 mmHg respectively, with both values being higher in males compared to females in all age groups (p < 0.001). Study participants with hyperlipidemia or diabetes, and those overweight, were almost twice as likely to be hypertensives, with the odds increasing to 4 for those obese (p for all, < 0.05). Stricter Mediterranean diet adherence significantly decreased the likelihood of hypertension by 36% (OR: 0.64; 95% CI: 0.439, 0.943), and a significant interaction was found between Mediterranean diet adherence and weight status on hypertension. The presence of hypertension is clustered with comorbidities, but is significantly associated with modifiable risk factors, including Mediterranean diet and weight status, underlining the need for personalized medical nutritional treatment.