Background Coronary artery disease (CAD) is a leading cause of death among the 38.4 million people with HIV globally. The extent to which cardiovascular polygenic risk scores (PRSs) derived in non‐HIV populations generalize to people with HIV is not well understood. Methods and Results PRSs for CAD (GPS _Mult ) and lipid traits were calculated in a global cohort of people with HIV treated with antiretroviral therapy with low‐to‐moderate atherosclerotic cardiovascular disease risk enrolled in REPRIEVE (Randomized Trial to Prevent Vascular Events in HIV). The PRSs were associated with baseline lipid traits in 4495 genotyped participants, and with subclinical CAD in a subset of 662 who underwent coronary computed tomography angiography. Among participants who underwent coronary computed tomography angiography (mean age, 50.9 [SD, 5.8] years; 16.1% women; 41.8% African, 57.3% European, 1.1% Asian), GPS _Mult was associated with plaque presence with odds ratio (OR) per SD in GPS _Mult of 1.42 (95% CI, 1.20–1.68; P =3.8×10 ⁻⁵ ), stenosis >50% (OR, 2.39 [95% CI, 1.48–3.85]; P =3.4×10 ⁻⁴ ), and noncalcified/vulnerable plaque (OR, 1.45 [95% CI, 1.23–1.72]; P =9.6×10 ⁻⁶ ). Effects were consistent in subgroups of age, sex, 10‐year atherosclerotic cardiovascular disease risk, ancestry, and CD4 count. Adding GPS _Mult to established risk factors increased the C‐statistic for predicting plaque presence from 0.718 to 0.734 ( P =0.02). Furthermore, a PRS for low‐density lipoprotein cholesterol was associated with plaque presence with OR of 1.21 (95% CI, 1.01–1.44; P =0.04), and partially calcified plaque with OR of 1.21 (95% CI, 1.01–1.45; P =0.04) per SD. Conclusions Among people with HIV treated with antiretroviral therapy without documented atherosclerotic cardiovascular disease and at low‐to‐moderate calculated risk in REPRIEVE, an externally developed CAD PRS was predictive of subclinical atherosclerosis. PRS for low‐density lipoprotein cholesterol was also associated with subclinical atherosclerosis, supporting a role for low‐density lipoprotein cholesterol in HIV‐associated CAD. Registration URL: https://www.reprievetrial.org ; Unique identifier: NCT02344290.