Background <p>Excessive gestational weight gain (EGWG) among women with overweight or obesity is a public health concern, increasing the risk of adverse pregnancy outcomes. Although lifestyle intervention has been proved effective on EGWG control, few successful mobile health-based lifestyle interventions exist in healthcare settings.</p> Methods <p>The Healthy Gestational Weight Gain program (HGWG-pro) is a two-centered randomized controlled trial that aims to evaluate the effectiveness of a multi-component intervention on promoting appropriate gestational weight gain, preventing gestational diabetes mellitus (GDM), and improving pregnancy, delivery, and neonatal outcomes among overweight or obese pregnant women aged 18 to 40 years old in China. Two maternal and child health care hospitals will be selected from the eastern region of China. Altogether 200 women with pre-pregnancy body mass index (BMI) ranging from 24 to 40&#xa0;kg/m² from the two hospitals will be randomized to intervention or control group. The intervention will be delivered from 10^+ 0-13^+ 6 weeks’ gestation to 32^+ 0–35^+ 6 weeks of gestation, with biweekly counseling sessions conducted either face-to-face during routine prenatal visits or via telephone, depending on the participant’s schedule. A smartphone application and wearable smart wristband will be used to assist in providing GWG related information, monitoring dietary behaviors, physical activity and weight, and providing feedback on weight and behaviors for participants. Data will be collected at 8^+ 0-13^+ 6, 24^+ 0-27^+ 6, and 32^+ 0-35^+ 6 weeks’ gestation, at delivery, at 42 days, 6 months and 12 months after delivery. This study has two primary outcomes: the between-group differences in gestational weight gain at 24^+ 0-27^+ 6 weeks’ gestation and 32^+ 0-35^+ 6 weeks’ gestation. The secondary outcomes will include differences between groups in weekly rate of GWG and incidence of adverse pregnancy complications and pregnancy outcomes, changes in diet, physical activity and other offspring health indicators at follow-up visits. Metabolic blood test results including indicators such as blood sugar and blood lipids will be extracted from the electronic medical record (EMR) system, indicators such as insulin and glycated hemoglobin will be measured through the collected blood samples. This trial includes a variety of process evaluation methods to evaluate the fidelity and adherence of the intervention.</p> Discussion <p>The HGWG-pro is one of the few mobile health-based interventions targeting EGWG among women with overweight or obesity in China. This multi-component intervention study is unique in its assessment of long-term maternal and infant health outcomes, extending up to 12 months postpartum, and the intervention methods based on mobile health contribute to yield an intervention model suitable for widespread application in healthcare settings.</p> Trial registration <p>ClinicalTrials.gov (NCT06370533): registered on 31th March 2024.</p>