Background: Hypertension (HTN) is a well-established cardiovascular (CV) risk factor in adults. The presence of HTN in children appears to predict its persistence into adulthood. Early diagnosis of HTN is crucial to reduce CV morbidity before the onset of organ damage. Aim: The aim of this study is to investigate cardiac damage in HTN, its risk factors (RFs), and evolution. Methods: We conducted a prospective/retrospective study involving children referred to the Childhood Hypertension Outpatient Clinic. This study included clinical and echocardiographic assessments of cardiac morphology and function at three time points: enrollment (T0) and follow-up (T1 and T2). Results: Ninety-two patients (mean age 11.4 ± 3 years) were enrolled. Cardiac eccentric and concentric hypertrophy were present in 17.9% and 9%, respectively, with remodeling in 10.5%. Overweight/obese subjects exhibited significantly higher systolic blood pressure (SBP), frequency of HTN, and body mass index (BMI) at T0 compared with patients with chronic kidney disease (CKD). SBP and BMI persisted more during follow-up. Normal-weight vs. overweight/obese patients were significantly more likely to have normal geometry. Positive correlations were found between BMI and left ventricular (LV) mass at T0, BMI and SBP at T0 and T1. Gender, BMI, SBP, and diastolic blood pressure (DBP) significantly predicted LV mass index (LVMI), but only BMI added significance to the prediction. During follow-up, the variation of BMI positively correlated with the variation of SBP, but not with LVMI. Conclusions: In our cohort, body weight is strongly associated with HTN and cardiac mass. Importantly, the variation in body weight has a more significant impact on the consensual variation of cardiac mass than blood pressure (BP) values. A strict intervention on weight control through diet and a healthy lifestyle from early ages might reduce the burden of CV morbidity in later years.