Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup. This temperature allows the meatballs to cook through while the vegetables soften perfectly without scorching.

In a large mixing bowl, combine ground turkey, panko breadcrumbs, eggs, milk, parmesan cheese, minced garlic, Italian seasoning, salt, and black pepper. Gently mix with your hands until just combined—overworking the mixture makes tough meatballs, so stop as soon as everything comes together.

Roll the turkey mixture into 24 meatballs about the size of golf balls and arrange them on your prepared sheet pan. Drizzle with olive oil and bake at 400°F for 12-15 minutes until the meatballs are mostly cooked through.

While the meatballs bake, mix your marinara sauce with the diced bell peppers, zucchini, and onion in a separate bowl. This easy sheet pan turkey meatballs recipe gets its flavor boost from vegetables releasing their juices directly onto the meatballs during the final cooking stage.

After 15 minutes, remove the sheet pan from the oven and pour the marinara-vegetable mixture over and around the partially cooked meatballs. Stir gently to combine and return to the oven.

Bake for an additional 10 minutes until the meatballs are cooked through and vegetables are tender. Sprinkle mozzarella cheese over everything and bake 2-3 more minutes until the cheese melts completely and becomes bubbly.

Remove from the oven and garnish with fresh parsley before serving. Let it rest for 2 minutes so the cheese sets slightly and everything stays together beautifully on the plate.