Background: Diffusion-weighted magnetic resonance imaging (DWI-MRI) is increasingly used as a non-contrast technique for the evaluation of focal liver lesions (FLLs). This study assessed the role of DWI and apparent diffusion coefficient (ADC) values in detecting and characterizing FLLs and explored an optimal ADC cut-off value to differentiate benign from malignant hepatic lesions. Materials and Methods: Seventy patients with clinically suspected or sonographically detected FLLs underwent ultrasonography, triphasic contrast-enhanced CT, and non-contrast MRI with DWI on a 1.5-T scanner. Lesions were assessed on conventional MRI sequences and ADC maps. Final diagnosis was established using histopathology, aspiration, surgery, additional imaging, or follow-up. Results: MRI with DWI identified a greater number of lesions than ultrasonography and triphasic CT. Ultrasonography showed a sensitivity of 73% and specificity of 88% for predicting malignancy, while triphasic CT demonstrated a sensitivity of 88% and specificity of 93%. DWI and ADC values showed high sensitivity (97%) and negative predictive value (98%) for malignant lesions. An ADC threshold of 1.4 × 10⁻³ mm²/s effectively differentiated benign from malignant lesions, with a statistically significant difference between mean ADC values of malignant and non-malignant lesions (p = 0.00001). Conclusion: Non-contrast MRI with DWI and ADC mapping provides excellent diagnostic performance in the evaluation of focal liver lesions, outperforming ultrasonography and performing comparably to contrast-enhanced CT. The proposed ADC cut-off serves as a reliable, non-invasive parameter for distinguishing benign from malignant lesions while avoiding radiation exposure and contrast-related risks.