Place the watermelon on a cutting board and use a sharp knife to remove the rind, exposing the bright red flesh underneath.
Cut the watermelon flesh into small, uniform cubes approximately 1 inch in size, ensuring even pieces for consistent freezing.
Transfer the watermelon cubes into a freezer-safe container, spreading them out evenly to prevent clumping.
Place the container in the freezer and freeze for at least 2 hours, or until the cubes are solid and icy to the touch.
Remove the frozen watermelon cubes from the freezer and serve immediately as a cold, juicy snack or garnish.