<p>Dynamic balance is a critical component of athletic performance, especially in soccer, influencing agility, change of direction, and injury prevention. The modified Star Excursion Balance Test (mSEBT) is a reliable and accessible tool to assess dynamic balance in athletes. Poor performance in the mSEBT is correlated with a higher risk of lower limb injuries in young athletes, highlighting the importance of understanding factors influencing its performance. We hypothesised a relationship between ankle dorsiflexion range of motion (ROM) and performance on the mSEBT in healthy young athletes, that could contribute to more precise assessment and intervention in clinical practice and sports. Twenty-six young soccer players participated in this cross-sectional observational study. Ankle dorsiflexion ROM was quantified using the weight bearing lunge test (WBLT), assessed with a digital inclinometer positioned 15&#xa0;cm from the anterior tibial tuberosity. Following a brief warm-up, athletes performed the mSEBT. Pearson correlation and linear regression analyses were conducted. A robust positive correlation was found between ankle dorsiflexion ROM and anterior reach (<i>p</i> = 0.001), with moderate correlations for posteromedial reach (<i>p</i> = 0.006) and composite score (<i>p</i> = 0.001). A weak correlation was observed for posterolateral reach (<i>p</i> = 0.048). Linear regression indicated that anterior reach explained 56% of the variance in dorsiflexion ROM (<i>R</i>² = 0.563, <i>p</i> &lt; 0.001), allowing a quick estimation of dorsiflexion mobility from a simple field test. Ankle dorsiflexion ROM showed significant correlations with multiple mSEBT directions, mainly influencing anterior reach performance, which accounted for 56% of its variance. These findings highlight the anterior reach of the mSEBT as a practical screening tool to estimate dorsiflexion mobility and support functional performance assessment in young soccer athletes.</p>