Background <p>This study compares the diagnostic performance of ultrasound (US) and magnetic resonance imaging (MRI) in detecting abnormalities such as ligament tears, tendon injuries, or fractures in the ankle, while also evaluating their clinical utility and limitations.</p> Methods <p>This study involved 83 patients with first-time ankle injuries. Surgical exploration served as the reference standard to compare and analyze US and MRI, evaluating sensitivity, specificity, positive predictive value (PPV, %), negative predictive value (NPV, %), accuracy (%), and area under the curve (AUC).</p> Results <p>US demonstrated significant diagnostic advantages for most ankle injuries, achieving 100% across all metrics for anterior talofibular ligament (ATFL) injury (<i>κ</i> = 1, AUC = 1). Moreover, US exhibited significantly higher overall diagnostic performance (AUC) compared to MRI for the calcaneofibular ligament (CFL), deltoid ligament (DL), peroneus longus tendon (PLT), and fracture detection. Conversely, MRI showed superior performance for syndesmotic (SDM) injury compared to US, with sensitivity rates of 46.67% versus 33.33% (AUC: 0.658 vs. 0.591), while maintaining 100% specificity for both ATFL injury and fracture. Both modalities demonstrated high sensitivity (100%) and excellent diagnostic value (AUC &gt; 0.9) for tibialis posterior tendon (TPT) injury.</p> Conclusion <p>This study confirms that US demonstrates superior performance in diagnosing superficial ligament injuries, specifically the ATFL and the CFL. In contrast, MRI is indispensable for evaluating deeper complex structures, such as the SDM and fracture lesions. Both modalities exhibit a complementary relationship in the diagnosis of ankle injuries.</p>