Preheat the oven to 350 degrees F (175 degrees C).
Place cherry tomatoes, bell peppers, zucchini, red onions, and garlic on a large, rimmed baking sheet. Drizzle and toss with olive oil. Season with basil and pepper.
Bake in the preheated oven until vegetables are lightly browned and easily pierced with a fork, 35 to 40 minutes.