Background: Understanding how sleep, sedentary behavior (SED), and physical activity (PA) (24-h movement profile) changes across pregnancy in individuals with prepregnancy overweight or obesity and how parity (previous births) impacts these changes can help inform interventions. Methods: In 155 participants, movement was measured using wrist-worn accelerometers, and sleep was self-reported in early (8–15 wk) and late (29–38 wk) pregnancy. The 24-hour movement profiles were analyzed using compositional analyses. Results: Nulliparous participants (no previous births) spent 33.95%, 38.14%, 25.32%, and 2.58% of the 24-hour day in early pregnancy in sleep, SED, light-intensity PA, and moderate/vigorous-intensity PA, respectively. Multiparous participants (≥1 previous birth) spent 2.50 percentage points less in SED (mean log-ratio difference = −0.068; 95% confidence interval [CI], −0.129 to −0.009) and 2.73 percentage points more in light-intensity PA (mean log-ratio difference = 0.102; 95% CI, 0.035 to 0.180). From early to late pregnancy, participants decreased the proportion of the 24-hour day spent asleep by 1.67 percentage points (mean log-ratio difference = −0.050; 95% CI, −0.092 to −0.011) and increased light-intensity PA by 1.56 percentage points (mean log-ratio difference = 0.057; 95% CI, 0.003 to 0.108), with no change in other behaviors. Conclusions: Nulliparous and multiparous individuals with prepregnancy overweight or obesity both had high levels of SED, with no change across pregnancy, and may require interventions to reduce  SED.