Obstructive sleep apnea is due to the complete or partial upper airway collapse occurring in OSA, resulting in hypoxia, defined as 3% or more oxygen desaturation episodes. Narrowed airway, reduced airway integrity due to various anatomic, genetic, or neuromuscular factors can contribute to the development of OSA The apnea-hypopnea index (AHI) is used to measure and score OSA. Cumulative apnea events and hypopnea events happened per hour during the patient’s sleep period are used to calculate AHI. OSA and hypertension are linked to each other as they share many common cofactors like age, obesity, and unhealthy lifestyles. Intermittent hypoxia has a significant role in the development of hypertension in OSA patients. This intermittent hypoxia induces endothelial dysfunction, overactivity of sympathetic effects, oxidative stress, and systemic inflammation leading to the development of resistant hypertension in OSA. This chapter summarizes the relationship between hypertension and obstructive sleep apnea, and the timely breakage of this linkage can yield a better lifestyle and long-term survival.