Measure and prepare all ingredients, then place the watermelon cubes in a large mixing bowl.
4 cups cubed watermelon
Add granulated sugar and lime juice to the watermelon. Stir with a rubber spatula until the sugar dissolves and the mixture is evenly combined, about 2 minutes.
0.5 cups granulated sugar, 2 tablespoons lime juice
Pour the mixture into a blender and blend on high until smooth and completely puréed, about 30 seconds. The mixture should be vibrant pink with no chunks remaining.
4 cups cubed watermelon, 0.5 cups granulated sugar, 2 tablespoons lime juice
Transfer the blended mixture to a freezer-safe container, smoothing the top with a spatula. Cover tightly with a lid or plastic wrap.
Freeze the mixture for at least 4 hours, stirring with a fork every 30 minutes during the first 2 hours to break up ice crystals and ensure a smooth texture.
Once fully frozen and scoopable, serve the watermelon sorbet in bowls, garnished with fresh mint or a lime wedge if desired.