Introduction: Breast cancer is the most prevalent malignancy and the leading cause of cancer related mortality among women worldwide. A palpable breast lump is a common clinical manifestation associated with both benign and malignant breast pathologies. Differentiating between benign and malignant breast lesions is crucial for appropriate patient management and treatment planning. Currently, the Breast Imaging-Reporting and Data System (BI-RADS) and Fine Needle Aspiration Cytology (FNAC) are utilized as initial diagnostic modalities for breast masses. Objective: To evaluate the diagnostic accuracy of Fine Needle Aspiration Cytology (FNAC) and Mammography in detecting malignant breast lesions in patients presenting with palpable breast lumps, using histopathology as the gold standard. Methodology: This cross sectional validation study was conducted in the Department of Histopathology, Holy Family Hospital, Rawalpindi, from October 30, 2021, to April 29, 2022. A total of 105 female patients presenting with palpable breast lumps were included in the study. Baseline demographic and socioeconomic data, including age, residential status, and socioeconomic background, were recorded. FNAC samples were obtained and processed in the Department of Histopathology for cytological assessment. The diagnosis of malignancy was established based on cytological and histopathological findings. Additionally, breast ultrasound was performed by an expert sonologist in the Department of Radiology to determine the BI-RADS score. The diagnostic outcomes of FNAC, BI-RADS, and histopathology were documented for each patient. Results: The mean age of the study participants was 41.04±11.00 years. Among them, 46 (43.81%) patients resided in rural areas, while 59 (56.19%) were from urban areas. Malignancy was detected in 42 (40.00%) cases using FNAC, whereas BI-RADS classified 44 (41.90%) cases as malignant. When evaluated against histopathology as the reference standard, BI-RADS demonstrated a sensitivity of 86.0%, specificity of 88.7%, positive predictive value (PPV) of 84.1%, and negative predictive value (NPV) of 90.2%. In comparison, FNAC exhibited a sensitivity of 93.0%, specificity of 96.8%, PPV of 95.2%, and NPV of 95.2%. Conclusion: The findings of this study indicate that both BI-RADS and FNAC are highly accurate and reliable diagnostic modalities for the evaluation of palpable breast lumps, with FNAC demonstrating superior diagnostic precision but the gold standard remains histopathological assessment.