Postoperative prognosis is better for hormonal receptor-positive breast cancer than for other phenotypes; however, there are no definitive predictive factors for relapse or survival. This study aimed to evaluate the maximum standardized uptake value (SUVmax) on 18F-fluoro-2-deoxy-glucose positron emission tomography/computed tomography (FDG-PET/CT) and clinicopathological characteristics as possible predictors of postoperative relapse-free survival (RFS) and overall survival (OS) in hormonal receptor-positive breast cancer patients. We evaluated 262 patients with Stage I–III breast cancer diagnosed as luminal type (luminal A, 166; luminal B, 96 patients) who underwent preoperative FDG-PET/CT between January 2006 and December 2011 at two institutions. The relationships among SUVmax and clinicopathological factors (age, clinical T/N stage, nuclear grade, lymph node metastasis and vascular invasion) were evaluated. A phantom study was performed to correct differences in PET/CT analysis between two institutions. The patients were divided according to the SUVmax cutoff on receiver operating characteristic (ROC) analysis for OS (≤6.0 group vs. >6.0 group, AUC = 0.742). Clinical T-factor and nuclear grade were significantly correlated with SUVmax (p < 0.0001 and p = 0.0092, respectively). In the uni- and multivariate analyses using the Cox model for relapse, SUVmax was significant (p = 0.013 and p = 0.055, respectively) among characteristics. RFS curves showed that prognosis was significantly better for the SUVmax ≤ 6.0 group than for the SUVmax > 6.0 group (p = 0.004). Similarly, SUVmax was significant for OS (p = 0.007 and p = 0.008). OS was significantly different between the SUVmax ≤ 6.0 and >6.0 groups (p < 0.001). SUVmax was useful for predicting outcomes in patients with luminal-type breast cancer.