No, watermelon is unlikely to cause acne and may even help reduce breakouts for some individuals.
While high glycemic index (GI) foods are generally thought to potentially worsen acne due to hormonal fluctuations, watermelon, despite its sweetness, is considered a good fruit to eat for skin health. This is likely due to its other beneficial components.
Therefore, while dietary factors can influence acne for some people, watermelon is not a likely culprit and may even be a beneficial addition to your diet for skin health.