Reducing the prevalence of hypertension, a major risk factor with significant health and economic implications is a target outlined by The World Health Assembly. This study investigated the prevalence of hypertension stages in Iran from 2005 to a projection for 2025 by three different guidelines. Eight nationally and sub-nationally representative cross-sectional WHO STEPwise approach to NCD risk factor surveillance (STEPS) studies were conducted from 2005 to 2021 in Iran. Staging followed the Joint National Committee's seventh report (JNC7), the American College of Cardiology/American Heart Association's 2017 guidelines (ACC/AHA), and the International Society of Hypertension's 2020 guidelines (ISH). Using data from a total of 210,546 participants, ACC/AHA projected higher prevalence in stage 1 and stage 2 hypertension, particularly 35–44 and 45–54 age groups of males, each reaching approximately 35% in 2025. Stage 1 hypertension demonstrated a stable trend (about 17%) for ISH and JNC7, whereas ACC/AHA exhibited a significant decrease from 37.07–30.32% between 2005 and 2025. Conversely, all guidelines indicated a significant decreasing trend for stage 2 hypertension from 2005 to 2025 (ACC/AHA: 26.60–23.27%, JNC7 and ISH: about 9–6.6%). The study indicated that the prevalence of hypertension stages has not remarkably changed based on all guidelines in recent years and is projected to remain stable by 2025. The choice of guidelines should consider cost-effectiveness analyses and the available resources.