Preheat oven to 425 degrees. Line a sheet pan with parchment paper or lightly grease with oil or oil spray.
Place potatoes, corn, sausage, and green beans in the center of your sheet pan. Drizzle with 2 tablespoons of oil then sprinkle with ½ teaspoon salt, ½ teaspoon Old Bay, and ½ teaspoon garlic powder. Spread ingredients into an even layer then place in the hot oven.
Meanwhile, in a bowl, toss shrimp with remaining tablespoon of oil, ¼ teaspoon Old Bay, ¼ teaspoon garlic powder, lemon zest, and a pinch of salt.
After 15 to 20 minutes (potatoes should be almost cooked through), remove pan from oven and scatter shrimp over the top. Return to oven and bake until shrimp is pink and curled, about 8 to 10 minutes.
Sprinkle with chopped parsley if desired and serve with fresh lemon wedges to squeeze on top.