Breast cancer during pregnancy presents unique therapeutic challenges, as effective maternal treatment must be balanced against potential risks to fetal and neonatal health. This systematic review aims to evaluate current evidence regarding the safety and effectiveness of chemotherapy during pregnancy in women with breast cancer (BC). This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive literature search was conducted in PubMed, Google Scholar, Scopus, and the Open Inter-university Consortium for Political and Social Research databases. Following the search and selection process, a total of 14 articles met the inclusion criteria. Risk of bias was assessed using design-specific Joanna Briggs Institute critical appraisal tools. The administration of specific chemotherapy regimens, mainly anthracyclines, after the first trimester was generally not associated with an apparent increase in congenital abnormalities or perinatal mortality. However, an increased risk of preterm birth was observed, with a substantial proportion of preterm deliveries being iatrogenic. Furthermore, available comparative evidence did not indicate substantially worse maternal oncological outcomes attributable to pregnancy itself. Taken together, these findings suggest that chemotherapy for BC during pregnancy can be administered with relative safety after the first trimester, within an individualized treatment approach and close collaboration among obstetricians, oncologists, and neonatologists. Nevertheless, further multicenter studies are required to fully elucidate long-term neonatal outcomes.