Maternal overweight has a substantial impact on reproductive, maternal, pregnancy, and neonatal outcomes with long-term and transgenerational health consequences. Interventions that aim to optimize periconception maternal lifestyle can improve maternal and fetal health during pregnancy and throughout the life course. However, it remains difficult to change and adopt adequate lifestyle behaviors. We hypothesize that additional psychological therapy targeting cognitive and affective factors substantially contribute to the effectiveness of these interventions. The proposed study aims to examine the feasibility and effectiveness of a blended personalized periconception lifestyle care intervention with additional psychological therapy aimed at women with a BMI≥25 and who are contemplating pregnancy or are already pregnant (≤12 weeks) in reducing inadequate lifestyle behaviors and improving early and late pregnancy outcome. The eHealth and Face-to-face Counseling (eFUSE) study follows a single-center two-arm randomized controlled trial design at the Erasmus MC, University Medical Center, with a multicenter regional referral. The female patients with overweight (BMI≥25), together with their male partner, will be stratified by pregnancy status (preconception vs pregnant) and randomized to receive either the blended personalized periconception lifestyle care intervention with additional psychological therapy (n=313) or usual care (n=313). The primary outcome is a change in the lifestyle risk score (between baseline and 24 weeks) between the randomization arms (difference in differences). Secondary outcomes include measurements defined as most relevant by the International Consortium for Health Outcomes Measurement, including behavioral determinants, patient satisfaction, provider feasibility, and maternal pregnancy and neonatal complications. The study will be open for recruitment from Fall 2021 onward. Data collection is expected to be completed by the beginning of 2023, and the results are expected to be published by Fall 2023. This study will evaluate the feasibility and effectiveness of a blended periconception lifestyle intervention with additional psychological therapy, aimed at women with a BMI≥25. Positive results of this innovative care approach will be used for implementation in routine medical care of all women with overweight, with the ultimate aim to improve clinical outcomes of these high-risk pregnancies. Netherlands Trial Register NL9264; https://www.trialregister.nl/trial/9264. PRR1-10.2196/28600. ©Melissa van der Windt, Sam Schoenmakers, Sten Willemsen, Lenie van Rossem, Régine Steegers-Theunissen. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 03.09.2021.