Purpose <p>Accurate staging of axillary lymph nodes plays a critical role in the management and prognostication of breast cancer (BC). The objective of this study was to compare the diagnostic value of ⁶⁸Ga-FAPI PET/CT and ¹⁸F-FDG PET/CT in assessing axillary lymph node metastases of BC.</p> Methods <p>This retrospective study included 42 female patients with histopathologically confirmed axillary lymph node metastases. All participants underwent both FDG and FAPI PET/CT imaging within the same week. SUVmax values of primary and metastatic lesions were recorded, and the results were subjected to statistical analysis.</p> Results <p>When the primary lesion ¹⁸F-FDG SUVmax (8.1 ± 5.8) was compared with ⁶⁸Ga- FAPI SUVmax (15.43 ± 6.4), ⁶⁸Ga-FAPI SUVmax was higher (<i>p</i> &lt; 0.0001). ¹⁸F-FDG detected lymph node metastases in 26 patients. ¹⁸F-FDG did not detect lymph node metastasis in 16 patients. ⁶⁸Ga-FAPI detected lymph node metastases in 39 patients. ⁶⁸Ga-FAPI failed to detect lymph node metastases in 3 patients. ⁶⁸Ga-FAPI was more effective than ¹⁸F-FDG in detecting axillary lymph node metastasis (<i>p</i> = 0.02 × 2 = 5.125). The SUVmax values of the detected lymph nodes were higher with ⁶⁸Ga-FAPI (10.3 ± 5.8) than with ¹⁸F-FDG (7.0 ± 4.3) (<i>p</i> = 0.015). The sensitivity of ⁶⁸Ga-FAPI (92.86%) was higher than that of ¹⁸F- FDG (61.9%).</p> Conclusions <p>Our findings demonstrate that ⁶⁸Ga-FAPI PET/CT provides superior diagnostic performance compared with ¹⁸F-FDG PET/CT in the detection of axillary lymph node metastases in BC patients. Compared with ¹⁸F-FDG, it provides greater sensitivity in detecting axillary lymph node metastases of BC.</p>