Abstract Background Hypertension-induced left ventricular hypertrophy (LVH) increases end-diastolic LV pressure and contributes to left atrial enlargement (LAE), which are associated with development of atrial fibrillation (AF). However, the impact of LVH and LAE and their regression following antihypertensive therapy on AF incidence remains unclear. Purpose This study aimed to investigate the impact of changes in the LVH and LAE status on the occurrence of new-onset AF (NOAF). Methods This retrospective analysis included patients with sinus rhythm who underwent echocardiography at hypertension diagnosis and after 6–18 months. LVH was defined as LV mass index >115 g/m2 (men) and >95 g/m2 (women), and LAE was defined as LA volume index >42 ml/m2. LVH and LAE regression was defined as the absence of LVH and LAE on follow-up echocardiography, respectively. The occurrence of NOAF was assessed in relation to changes in LVH and LAE status. Results Among the 1,464 patients included in the study, 163 (11.1%) patients developed NOAF during a median follow-up of 63.8 months (interquartile range, 35.9–128.5 months). On average, 12 electrocardiograms per patient were reviewed for AF detection. New-onset LVH (adjusted HR 1.88, 95% CI 1.20–2.94, P=0.006) and LAE (adjusted HR 1.89, 95% CI 1.05–3.40, P=0.034) were significant predictors of NOAF. Conversely, regression of LVH (adjusted HR 0.51, 95% CI 0.280.91, P=0.022) or LAE (adjusted HR: 0.30, 95% CI 0.15–0.63, P=0.001) after antihypertensive therapy was associated with a reduced risk of NOAF. The risk of NOAF was higher in patients with LVH and LAE together (adjusted HR 4.30, 95% CI 2.81–6.56, P<0.001) than in those with either LVH or LAE, or those with neither, as determined by follow-up echocardiography. Conclusion In patients with hypertension and sinus rhythm, regression of LVH and LAE following antihypertensive therapy is associated with a decreased incidence of NOAF, whereas newly developed LVH or LAE is associated with a higher risk of NOAF. The changes in left heart geometry can serve as a predictive marker for NOAF in patients with hypertension.