Aim and Objectives: The objective of this study was to illustrate the link between periodontitis (PO) and endothelial dysfunction in hypertensive patients. Materials and Methods: This cross‑sectional study involved 53 hypertensive patients with or without PO compared with 28 healthy controls. On the basis of the study protocol, the participants were divided into three groups: Group (1): 24 patients with hypertension only, Group (2): 29 patients with hypertension and PO, and Group (3): 28 healthy controls. Lipid profile, endothelin‑1 (ET‑1), and high‑sensitivity C‑reactive protein (hs‑CRP) were measured. Blood pressure and body mass index (BMI) were evaluated. Diagnostic criteria of severe PO periodontal indices including plaque index, gingival index, and community periodontal index were estimated. Data collected during the study were analyzed using analysis of variance followed by Bonferroni post hoc test and unpaired t‑test (IBM SPSS Statistics for Windows, version 20.0, 2014, IBM, Armonk, NY). Results: BMI was not differed in both groups, P = 0.08. Systolic blood pressure and diastolic blood pressure were high in hypertensive patients with PO compared with hypertensive patients only, P = 0.04 and P = 0.03, respectively. Moreover, hypertensive patients with PO showed significant dyslipidemic status compared with hypertensive patients only (P < 0.05). Biomarker of endothelial dysfunction (ET‑1) was elevated in patients with PO (67.54 ± 13.56 pg/mL) compared with hypertensive patients only (23.67 ± 9.63 pg/mL), P = 0.0001. hs‑CRP serum level was increased patients with PO compared with hypertensive patients only, P = 0.002. PO indices were high in patients with PO compared with hypertensive patients only, P < 0.01. Conclusion: ET‑1 serum level is elevated in hypertensive patients with severe PO and correlated with cardio‑metabolic complications, mainly endothelial dysfunction. Therefore, ET‑1 serum level is regarded as a surrogate biomarker link PO with risk of endothelial dysfunction.