Breast cancer is the most common cancer diagnosed in women, and early stages are treated with lumpectomy and irradiation. Irradiation, however, leads to reduced vascularization and fibrosis, which may influence the cosmetic outcome unfavourably and increase complications after subsequent surgery on irradiated breasts. Patients with significant asymmetry after treatment may desire corrective reduction mammoplasty or mastopexy, but this may be associated with increased complication rates. This systematic review and meta-analysis aimed to investigate postoperative complication rates after bilateral reduction mammoplasty or mastopexy in women who had undergone unilateral lumpectomy and irradiation. PubMed, Medline, EMBASE and Cochrane databases were searched for eligible studies. After screening titles and abstracts, 14 full text studies were reviewed, and 7 of these were included in the analysis. The meta-analysis showed a significantly higher complication rate in the irradiated breast compared to the non-irradiated breast, rate ratio 4.82 (95% CI: 1.58, 14.70), p = 0.006. The complication rate was 54% in the irradiated breast (58/107) compared to 8% (9/107) in the non-irradiated breast (p = 0.034). This study suggests that reduction mammoplasty or mastopexy in the previously irradiated breast is associated with a significantly increased risk of complications. Careful patient selection and information are paramount in the treatment of this patient group.