Background $^{18}F$-fluorodeoxyglucose ($^{18}F$-FDG) positron emission tomography ((PET) safely predicts axillary status in patients with breast cancer, but is not sufficiently accurate in early breast cancer patients. This study analyzed the value of $^{18}F$-FDG PET/computed tomography (CT) with contrast enhancement in detecting axillary lymph node involvement in T1 breast cancer patients. Methods Contrast-enhanced $^{18}F$-FDG PET/CT was performed within 20 days of surgery in 143 breast cancer patients with tumors ${leq}$2 cm in size. The patients underwent either axillary lymph node dissection (ALND) or sentinel lymph node biopsy (SLNB), and histopathology reports were used to provide the definitive diagnosis against which the contrast-enhanced $^{18}F$-FDG PET/CT study results were compared. Results The sensitivity, specificity, and negative and positive predictive values of contrast-enhanced $^{18}F$-FDG PET/CT in detecting axillary involvement were 70.0%, 92.2%, 88.8%, and 77.8%, respectively, in the entire series of 143 patients, with eight false-positive and 12 false negative results. The false-negative results were associated with the number of metastatic lymph nodes and the rate of FDG uptake. Conclusion Contrast-enhanced $^{18}F$-FDG PET/CT cannot replace histologic staging using SLNB in patients with breast cancer, but $^{18}F$-FDG PET/CT increases the sensitivity for predicting axillary node metastasis, and allows for a selective approach to either ALND or SLNB, even in patients with T1 breast cancer.