1. Background: With the rising prevalence of hypertension, especially among younger populations, there is a critical need to better assess health status and predict associated complications. This study developed a biological age model ("hypertension age") for hypertensive patients to predict the risk and timing of major complications. 2. Methods: Using South Korea's NHIS-NHID data, researchers analyzed 4,535,041 hypertensive patients who underwent health examinations between 2009 and 2010. Patients were followed for an average of 12.40 years (until 2022). Principal Component Analysis (PCA) was used to develop the biological age (cBA) model. The risk and onset timing of complications were analyzed using Cox proportional hazards and multiple regression models, adjusting for variables like medication use and baseline diseases. 3. Results: A 1-standard deviation (SD) increase in the age gap?where biological age exceeds chronological age (cBA - CA)?was significantly associated with an elevated risk for all major complications in both sexes (p < 0.001). Furthermore, a 1-SD increase in this gap significantly accelerated the time to complication onset for nearly all conditions (p < 0.001), with the exception of dementia in women. The impacts of medication use, hypertension duration, and baseline comorbidities varied by specific complication. 4. Conclusions: Lowering "hypertension age" relative to chronological age can significantly reduce the risk and delay the onset of major cardiovascular and related complications. Quantifying this biological age gap serves as a powerful motivational tool for personalized health management and complication prevention in hypertensive patients.