Background Recent trials support the role of cardiac CT in the evaluation of symptomatic patients suspected of having coronary artery disease (CAD); however, body mass index (BMI) has been reported to negatively impact CT image quality. Purpose To compare initial use of CT versus invasive coronary angiography (ICA) on clinical outcomes in patients with stable chest pain stratified by BMI category. Materials and Methods This prospective study represents a prespecified BMI subgroup analysis of the multicenter Diagnostic Imaging Strategies for Patients with Stable Chest Pain and Intermediate Risk of Coronary Artery Disease (DISCHARGE) trial conducted between October 2015 and April 2019. Adult patients with stable chest pain and a CAD pretest probability of 10%-60% were randomly assigned to undergo initial CT or ICA. The primary end point was major adverse cardiovascular events (MACE), including cardiovascular death, nonfatal myocardial infarction, or stroke. The secondary end point was an expanded MACE composite, including transient ischemic attack, and major procedure-related complications. Competing risk analyses were performed using the Fine and Gray subdistribution Cox proportional hazard model to assess the impact of the relationship between BMI and initial management with CT or ICA on the study outcomes, whereas noncardiovascular death and unknown causes of death were considered competing risk events. Results Among the 3457 participants included, 831 (24.0%), 1358 (39.3%), and 1268 (36.7%) had a BMI of less than 25, between 25 and 30, and greater than 30 kg/m2, respectively. No interaction was found between CT or ICA and BMI for MACE (P = .29), the expanded MACE composite (P = .38), or major procedure-related complications (P = .49). Across all BMI subgroups, expanded MACE composite events (CT, 10 of 409 [2.4%] to 23 of 697 [3.3%]; ICA, 26 of 661 [3.9%] to 21 of 422 [5.1%]) and major procedure-related complications during initial management (CT, one of 638 [0.2%] to five of 697 [0.7%]; ICA, nine of 630 [1.4%] to 12 of 422 [2.9%]) were less frequent in the CT versus ICA group. Participants with a BMI exceeding 30 kg/m² exhibited a higher nondiagnostic CT rate (7.1%, P = .044) compared to participants with lower BMI. Conclusion There was no evidence of a difference in outcomes between CT and ICA across the three BMI subgroups. Clinical trial registration no. NCT02400229