Background <p>To examine physical activity (PA) among US military servicemembers (SM) with overweight and obesity (OW/OB) and if they meet Physical Activity Guidelines (PAG). To assess differences in PA by sex and associations between PA and body composition.</p> Methods <p>PA duration and intensity were objectively collected via accelerometers and self-reported daily average via self-report International Physical Activity Questionnaire (IPAQ) among US active-duty SM (<i>n</i>=113, 58% female, Mean BMI = 33.3 ± 3.9 kg/m2). Sex, body mass index (BMI), and body fat % (BF% via circumference and an equation) were measured. Accelerometer PA and sedentary time were computed for IPAQ categories who met PAG. PA sex differences were assessed with t-tests and chi-square. Pearson correlations examined associations between PA, BMI, and BF%.</p> Results <p>Accelerometry showed SM engaged in a daily average of 93 minutes of moderate to vigorous PA (MVPA), 145.2 minutes of light, and 307 minutes of sedentary activity. The IPAQ showed SM engaged in 91 minutes of MVPA, 121.1 minutes of walking, and 423 minutes sitting. Males engaged in more accelerometer-derived MVPA (<i>p</i> = 0.04) than females. Accelerometry showed 100% of SM met the PAG while the IPAQ showed 90% met the PAG. The IPAQ and accelerometer MVPA metrics were correlated (r = 0.26; <i>p</i> &lt; 0.01). Sedentary time was correlated with BMI (r = 0.25; <i>p</i> &lt; 0.01). Sitting was correlated with BF % (r = -0.26; <i>p</i> = 0.02).</p> Conclusions <p>Overall, SM with OW/OB meet PAG. PA levels among SM are related to sex, BMI, and BF%.</p>