Preheat oven to 425F. Line a baking sheet with parchment paper.
Place the peppers, onions, and garlic onto the baking sheet. Drizzle with olive oil, season with salt, pepper, and Italian seasoning. Toss to evenly coat the veggies and create a space in the center of the pan and add the chicken sausage links.
Bake for 20 to 25 minutes or until the sausage is cooked through and the veggies tender. Remove the baking sheet from the oven and allow to rest 5 minutes before slicing the sausage and serving with peppers and onion.