Preheat your oven to 350°F (175°C).
In a skillet, sauté the chopped onion, bell pepper, and garlic over medium heat until they are softened, about 5 minutes. Remove from heat and let cool slightly.
In a large mixing bowl, combine the ground chicken, breadcrumbs, sautéed vegetables, milk, egg, 2 tablespoons of ketchup, Worcestershire sauce, oregano, salt, and pepper.
Mix all the ingredients together until well combined. Be careful not to overmix, as this can make the meatloaf tough.
Transfer the mixture to a loaf pan and shape it into a loaf. Brush the top with the remaining ketchup.
Place the loaf pan on a baking sheet (optional, for easier handling) and bake in the preheated oven for 50 minutes, or until the internal temperature reaches 165°F (74°C).
Allow the meatloaf to rest for 10 minutes before slicing and serving.