Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
In a large bowl, combine ground chicken, bread crumbs, milk, egg, minced garlic, Italian seasoning, salt, and pepper. Mix gently until just combined. Do not overmix.
Roll the mixture into 1-inch meatballs and place them on the prepared baking sheet.
Bake for 20 minutes, or until the meatballs are cooked through and lightly browned.
While the meatballs are baking, heat the marinara sauce in a saucepan.
Add the baked meatballs to the marinara sauce and simmer for 5 minutes to allow the flavors to meld.
Notes
Serve chicken meatballs over pasta, rice, or zucchini noodles. Garnish with fresh parsley and grated Parmesan cheese, if desired.