Introduction and objective <p>The natural product watermelon contains a high concentration of antioxidants that have the potential to mitigate the oxidative damage resulting from the generation of free radicals’ post-exercise. As such, this study aims to explore the impact of 6&#xa0;weeks of watermelon juice supplementation on the antioxidant capacity and vo₂max of elite female taekwondo athletes.</p> Methods <p>In a study involving 25 young female elite taekwondo players with a mean age of 21.84 ± 2.26&#xa0;years, participants were randomly assigned to either the watermelon juice group (<i>n</i> = 15) or the placebo group (<i>n</i> = 10). Over 6&#xa0;weeks, subjects consumed 50&#xa0;ml of watermelon juice ingestion (WJI) or placebo (PLA) 45&#xa0;min before each of their three weekly training sessions. The Total Antioxidant Capacity (TAC) index was measured in selected athletes undergoing training at the Taekwondo House in Kermanshah, located in western Iran.</p> Results <p>The study found that following 6&#xa0;weeks of intervention, watermelon juice supplementation led to a significant increase in total antioxidant capacity (TAC) (<i>t</i> = −&#xa0;5.954, <i>p</i> = 0.001), while the TAC levels in the placebo (PLA) group remained relatively unchanged (<i>t</i> = 0.720, <i>p</i> = 0.490). Moreover, participants in the watermelon juice group experienced significantly lower levels of muscle soreness at 24 and 48&#xa0;h post-exercise (<i>p</i> &gt; 0.05).</p> Conclusions <p>A 6&#xa0;weeks regimen of watermelon juice supplementation has been found to enhance overall antioxidant capacity and alleviate muscle soreness.</p>