Informal employment can impact the continuation of breastfeeding. Therefore, the objective of this study is to analyze the available scientific evidence on breastfeeding and the barriers faced by women working in informal employment contexts. A scoping review was conducted following the guidelines of the Joanna Briggs Institute and the PRISMA-ScR checklist. A search was carried in the PubMed, Scopus, EBSCO, and Web of Science databases, without language or year restrictions. Original studies that analyzed barriers to breastfeeding in informal employment contexts were included. Data selection and extraction were performed independently by two reviewers, with discrepancies resolved by consensus. Eight studies conducted in Mexico, India, South Africa, Uganda, Ghana, and Brazil were included. The main barriers identified were the absence of policies, early return to work due to economic necessity, personal valuation of breastfeeding, and family and partner support. The role of prenatal care and the mother’s mental health is highlighted. Complementary international evidence reinforces that labor and sociocultural inequalities limit the practice of exclusive breastfeeding. Informal employment is a structural determinant that hinders breastfeeding. In addition, the lack of public policies, economic pressure, as well as personal and immediate environment factors, such as family, are barriers that impact successful breastfeeding.