This is the first longitudinal study evaluating whether adiposity is associated with inter‐arm blood pressure difference. We evaluated 714 overweight/obese individuals aged 40‐65 years over a 3‐year follow‐up. Systolic and diastolic blood pressures were measured in both arms simultaneously using an automated machine. Linear regression assessed the associations of body mass index, fat %, waist, neck, thigh, and arm circumferences (cm), with absolute inter‐arm differences in systolic (IAS) and diastolic (IAD) blood pressure (mm Hg). Poisson regression was used for binary outcomes (IAS and IAD ≥ 10 mm Hg). All models were adjusted for age, gender, smoking, physical activity, and HOMA‐IR. Adiposity measures were associated with increased IAS and IAD (β range: 0.09‐0.20 and 0.09‐0.30). Neck circumference showed the strongest association with IAS (β = 0.20, 95% CI: 0.03, 0.37) and IAD (β = 0.30, 95% CI: 0.12, 0.47); arm circumference showed a similar association with IAS, but lower with IAD. Highest quartiles of BMI, thigh, and arm showed significant associations with IAS (IRR: 2.21, 2.46 and 2.70). Highest quartiles of BMI, waist, neck, and arm circumferences were significantly associated with IAD (IRR: 2.38, 2.68, 4.50 and 2.24). If the associations are corroborated in other populations, adiposity may be an important modifiable risk factor for inter‐arm blood pressure difference with a large potential public health impact.