Cut the watermelon into small, uniform cubes approximately 1 inch in size on the cutting board using a sharp knife.
Arrange the watermelon cubes in a single layer on a baking sheet or tray, ensuring they do not overlap or stack too much.
Place the tray with watermelon cubes into the freezer and freeze until solid, about 2-3 hours.
Once frozen, remove the tray from the freezer and let sit at room temperature for a minute or two to ease handling.
Use tongs or a fork to serve the frozen watermelon cubes directly as a cold, crunchy snack or dessert.