Preheat the oven to 425°F (220°C).
Line a large sheet pan with parchment paper or lightly grease it.
Place the potatoes, sausage, bell pepper, and onion on the prepared sheet pan.
Drizzle everything with olive oil.
Sprinkle with garlic powder, Italian seasoning, paprika, salt, and black pepper.
Toss until all ingredients are evenly coated.
Spread the mixture into a single layer.
Bake for 35 to 40 minutes, stirring halfway through cooking.
Continue roasting until the potatoes are tender and golden brown and the sausage is lightly crisped.
Remove from the oven and garnish with fresh parsley if desired.
Serve immediately.