Use a sharp knife and cutting board to dice the watermelon into roughly 1-inch cubes, ensuring they are evenly sized for texture consistency.
Slice the peeled and pitted avocado in half, then carefully cut into cubes similar in size to the watermelon pieces.
Place the watermelon and avocado cubes into a large mixing bowl.
Gently toss the ingredients together using a spoon or spatula, ensuring an even distribution without mashing the delicate pieces.
Serve immediately, showcasing the bright, colorful mixture with the contrasting textures of juicy watermelon and creamy avocado.