The increasing prevalence of overweight and obesity worldwide represents a (chronic) complex public health problem. This is also seen among women of childbearing age despite increased efforts to promote physical activity (PA) interventions. Excessive gestational weight gain (GWG) is associated with negative health outcomes for both mothers and offspring. To summarize current systematic reviews (SRs) on PA interventions during pregnancy and postpartum to prevent excessive GWG and identify the most effective approaches. A literature search was conducted on major electronic databases (MEDLINE/Pubmed, Cochrane, Web of Science, Epistemonikos) from inception to March 2023. This study included SRs and meta-analyses of studies involving women aged 18 years or older from diverse ethnic backgrounds, who were either in the preconception period, pregnant, or within 1 year postpartum and who had no contraindications for exercise. Women with chronic diseases, such as pre-existing diabetes (type 1 or type 2) were excluded. Two reviewers extracted data from selected studies assessing the impact of PA in preconception, pregnancy, and postpartum. Methodologic quality was assessed with the AMSTAR-2 tool. A narrative summary of results addresses relationships between PA and weight before, during, and after pregnancy, informing future research priorities for preventing excessive weight gain. This study is registered on PROSPERO (CRD420233946666). Out of 892 identified articles, 25 studies were included after removing duplicates, unrelated titles, and screening titles and abstracts for eligibility. The results demonstrate that PA can help prevent excessive GWG and postpartum weight retention. Structured and supervised moderate-intensity exercise, at least twice a week, and each session lasting a minimum of 35 min seems to provide the greatest benefits. Women who comply with the PA program and recommendations are more likely to achieve adequate GWG and return to their pre-pregnancy body mass index after delivery. Further research is warranted to explore how preconception PA influences pregnancy and postpartum outcomes given the absence of identified preconception-focused interventions.