Background Diabetes and hypertension have been associated with adverse left ventricular (LV) remodeling. While they often occur concurrently, their individual effects are understudied. We aimed to assess the independent effects of diabetes and hypertension on LV remodeling in Black adults. Methods and Results The JHS (Jackson Heart Study) participants (n=4143 Black adults) with echocardiographic measures from baseline exam were stratified into 4 groups: neither diabetes nor hypertension (n=1643), only diabetes (n=152), only hypertension (n=1669), or both diabetes and hypertension (n=679). Echocardiographic measures of LV structure and function among these groups were evaluated by multivariable regression adjusting for covariates. Mean age of the participants was 52±1 years, and 63.7% were women. LV mass index was not different in participants with only diabetes compared with participants with neither diabetes nor hypertension ( P =0.8). LV mass index was 7.9% (6.0 g/m ² ) higher in participants with only hypertension and 10.8% (8.1 g/m ² ) higher in participants with both diabetes and hypertension compared with those with neither ( P <0.001). LV wall thickness (relative, posterior, and septal) and brain natriuretic peptide levels in participants with only diabetes were not significantly higher than participants with neither ( P >0.05). However, participants with both diabetes and hypertension demonstrated higher LV wall thickness and brain natriuretic peptide levels than participants with neither ( P <0.05). Conclusions In this cross‐sectional analysis, diabetes was not associated with altered LV structure or function in Black adults unless participants also had hypertension. Our findings suggest hypertension is the main contributor to cardiac structural and functional changes in Black adults with diabetes.