Background: Sentinel lymph node biopsy (SLNB) is the standard staging procedure for early-stage, clinically node-negative breast cancer, often replacing axillary lymph node dissection (ALND). Methylene blue dye (MBD) offers a cost-effective alternative to radioisotopes, particularly in resource-limited settings. Objective: This study evaluated the efficacy of SLNB using the MBD injection technique in early breast cancer patients. Methods: A cross-sectional study was conducted at SIMS&RC from June 2023 to September 2024, involving 40 patients with T1/T2 breast tumors and no clinical or radiological axillary lymph node involvement. SLNB was performed using MBD, followed by histopathological evaluation. Identification rate, accuracy, sensitivity, specificity, predictive values, and false-negative rate were calculated. Results: The identification rate was 100%, with an accuracy of 94.73%. Sensitivity was 93.75%, specificity was 100%, positive predictive value (PPV) was 100%, negative predictive value (NPV) was 75%, and the false-negative rate was 6.25%. Of the 40 patients, 85% underwent mastectomy, and 15% had breast-conservative surgery. SLN positivity was confirmed in 37.5% of cases on histopathology. Conclusion: The MBD technique demonstrated high accuracy and reliability for SLNB in early breast cancer, supporting its use in settings lacking nuclear medicine facilities. Its low false-negative rate and cost-effectiveness make it a viable alternative.