Cut the watermelon into bite-sized cubes—roughly 1-inch pieces.
Using a small spoon or melon baller, scoop out a tiny bit of the top of each cube.
Spoon a small dollop of chilled goat cheese into each indent.
Garnish each bite with a tiny mint leaf.
Secure with a toothpick if serving on a platter or outdoors.
Serve immediately or refrigerate for up to 1 hour before serving.