Objectives <p>To explore the impacts of a mobile health intervention on weight control, pregnancy outcomes, and health-promoting lifestyle profiles among overweight pregnant women.</p> Methods <p>A longitudinal, repeated-measures, randomized controlled trial. We enrolling 112 pregnant women classified as overweight pre-pregnancy. The intervention group received mobile-based health education for mom and baby (mHEMB) intervention for 6–8 months, whereas the control group received usual care. Women in both groups filled out a questionnaire to provide demographic and health information at time 1 (prior to 20 weeks of gestation). Body weight and health-promoting lifestyle profiles were assessed at time 1, time 2 (36–40 weeks of gestation), and time 3 (6–12 weeks postpartum). Maternal and neonatal outcomes were assessed at the time of delivery.</p> Results <p>Intervention participants gained less weight during pregnancy. The postpartum weight gain in the intervention group was significantly lower than that in the control group. The proportion of women who exceeded Institute of Medicine guidelines was significantly smaller in the intervention group than in the control group. With the exception of stress management, the scores for the health-promoting lifestyle profiles in the intervention group were significantly higher than those in the control group at time 2. No significant differences were noted in the health-promoting lifestyle profiles between the two groups at time 3.</p> Conclusions for Practice <p>The mHEMB provides pregnant women with the necessary skills and support to adopt long-term behavioral changes, with significant effects on weight control during pregnancy.</p> Trial Registration <p>ClinicalTrials.gov NCT03726983.</p>