Background: Adjuvant radiotherapy could be a necessary step in the oncological treatment for breast cancer. However, radiotherapy may have negative effects on implant-based immediate breast reconstruction. The aim of this study was to determine the impact of adjuvant radiation therapy on surgical results and patientreported satisfaction outcomes in women undergoing immediate implant-based breast reconstruction. Methods: A systematic search in PubMed was conducted on September 2019 and updated on April 2021. The risk of bias of the included studies was assessed using the Newcastle-Ottawa Quality Assessment Form for Observational Studies. RevMan 5 was used for statistical analysis. We obtained relative risks to determine the complication incidence and mean differences for 2-year BREAST-Q scores. Results: Fourteen studies were included. A total of 11,958 implant-based immediate reconstructions were performed, 2311 received postmastectomy radiation therapy, and 9647 were considered as control group. Surgical complications, reoperation rates, and reconstruction failure were significantly higher among irradiated breasts. Significantly lower BREAST-Q scores were reported by irradiated women receiving radiotherapy. Conclusions: This systematic review and meta-analysis combines reconstruction complication rates with aesthetic and patient-reported satisfaction outcomes. Adjuvant radiotherapy is consistently associated with greater complication rates and poorer aesthetic and satisfaction outcomes. The magnitude of association is significantly lower when the reconstruction is based on autologous tissues.