Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Pat the chicken breast dry with paper towels and cut into 1-inch bite-sized cubes.
Peel and cube the sweet potato into 1/2-inch pieces to ensure they cook at the same rate as the chicken.
In a large mixing bowl, combine the chicken, sweet potato, diced bell peppers, and red onion.
Drizzle the olive oil over the mixture and sprinkle with garlic powder, smoked paprika, sea salt, and black pepper.
Toss everything thoroughly until the ingredients are evenly coated in oil and spices.
Spread the hash in a single layer on the prepared baking sheet, making sure not to overcrowd the pan so the vegetables roast rather than steam.
Roast for 20 to 25 minutes, tossing the ingredients halfway through, until the chicken is cooked through and the potatoes are fork-tender.
Remove the pan from the oven, add the chopped kale, and toss it with the hot ingredients for 2 to 3 minutes until the kale is just wilted and slightly crisp.