Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into uniform 1-inch cubes and dice the sweet potato into small 1/2-inch pieces to ensure they cook at the same rate.
Chop the broccoli into bite-sized florets and slice the red bell pepper into 1-inch wide strips.
In a small glass bowl, whisk together the extra virgin olive oil, fresh lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Place the chicken cubes, sweet potatoes, broccoli, and peppers onto the prepared sheet pan.
Pour the lemon-herb dressing over the ingredients and use your hands or tongs to toss everything until thoroughly and evenly coated.
Spread the mixture out into a single layer, ensuring the chicken and vegetables aren't overcrowded.
Roast in the center of the oven for 20-25 minutes, or until the chicken is cooked through and the sweet potatoes are fork-tender and slightly caramelized.