Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Dice the chicken breast and sweet potato into uniform 1-inch cubes to ensure they cook at the same rate.
Chop the broccoli into bite-sized florets and slice the red bell pepper into thin strips.
Arrange the chicken, sweet potato, broccoli, and bell pepper in a single layer on the prepared sheet pan.
Drizzle the olive oil over the ingredients and sprinkle evenly with sea salt, black pepper, garlic powder, and dried oregano.
Toss the ingredients thoroughly with your hands or a spatula until every piece is well-coated with the oil and seasonings.
Spread the mixture out across the pan, ensuring there is space between the pieces to allow them to roast rather than steam.
Place the pan in the oven and roast for 20 to 25 minutes, or until the chicken is cooked through and the sweet potatoes are fork-tender.
Transfer the roasted chicken and vegetables into a large bowl and serve immediately while warm.