Accurate prediction of sentinel lymph node (SLN) involvement is central to surgical planning in breast cancer. This study assessed whether lymph node adiposity (LNA)—fat enlargement visible on mammography—adds predictive value to the Memorial Sloan Kettering (MSK) SLN nomogram. A retrospective review identified patients with pre-operative MRI and sufficient clinical data from 2011–2019. Predictive performance was quantified using area under the curve (AUC) for three models: MSK nomogram alone (AUC = 0.71), LNA alone (0.65), and MSK nomogram + LNA (0.75). The combined model outperformed either alone, indicating that LNA independently contributes to SLN metastasis risk stratification. As surgical management trends toward less invasive axillary evaluation, pre-operative tools that enhance diagnostic precision may increasingly guide decision-making. These results support incorporating LNA into existing predictive algorithms to improve individualized surgical planning.