Objective: To identify and analyze the scientific evidence on the mental health of postpartum women during the COVID-19 pandemic. Method: This integrative review was carried out using the VHL, CINAHL, PubCovid, Scopus, and Web of Science databases, whose research question was “What is the scientific evidence on the mental health of postpartum women during the SARS-CoV-2 pandemic?” Results: Ten articles in English were included, identifying a higher frequency of cross-sectional research (n = 4), publications in November 2020 (n = 3), conducted in Italy (n = 3), with level VI evidence (n = 6). The study found that postpartum women feel depressed, lonely, and afraid; attention is drawn to the worsening risk of postpartum depression with significant prevalence values. It points out factors that negatively influence the mental health of this population in the current pandemic and discloses care measures. Conclusions: In addition to previous characteristics, socioeconomic conditions (e.g., living in highly infected areas, unemployment) and elements inherent to this pandemic (e.g., distance and fear of contagion) negatively influence the mental health of postpartum women. Means of dealing with the conditions imposed by the COVID-19 pandemic are available, such as relaxation techniques, physical exercise, and professional support. The relevance and need for research on this theme, mostly nationally, are highlighted.