Gather ingredients. Preheat the oven to 425 degrees F (220 degrees C). Spray a large sheet pan with cooking spray.

Place potatoes into a large pot and cover with salted water; bring to a boil. Reduce heat to medium-low and simmer until tender, about 10 to 12 minutes.

Add corn and boil for an additional 5 minutes. Drain. Cut corn into thirds.

Meanwhile, whisk 3 tablespoons olive oil, 3 tablespoons Creole seasoning, lemon juice, garlic, Italian seasoning, 1/2 teaspoon paprika, red pepper flakes, salt, and ground black pepper together in a small bowl until combined.

Combine boiled potatoes and corn, all the bell peppers, cherry tomatoes, onion, and sausage slices in a large bowl. Add seasoning mixture and mix evenly.

Spread potato mixture onto a sheet pan in a single layer. Place lemon wedges evenly on all sides of the sheet pan.

Bake in the preheated oven for 8 minutes.

Meanwhile, combine shrimp, remaining 1 tablespoon olive oil, remaining 1/2 teaspoon paprika, and remaining 1/2 teaspoon Creole seasoning in a bowl. Marinate for a few minutes.

Add shrimp to the sheet pan with the potato mixture after 8 minutes of baking and mix to combine.

Return sheet pan to the oven and bake until shrimp are opaque and reach 145 degrees F (63 degrees C), 6 to 8 minutes. Remove lemon wedges. Garnish with parsley and green onion before serving.