Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Dice the sweet potato into 1/2-inch cubes and chop the bell pepper into 1-inch pieces.
Cut the chicken breast into bite-sized 1-inch chunks to ensure even cooking with the vegetables.
In a large mixing bowl, whisk together the olive oil, minced garlic, rosemary, thyme, sea salt, and black pepper.
Add the chicken, sweet potatoes, and bell peppers to the bowl and toss thoroughly until everything is well-coated in the herb oil.
Spread the mixture in a single layer on the prepared sheet pan, ensuring nothing is overcrowded so the vegetables roast rather than steam.
Roast for 20-25 minutes, tossing halfway through, until the chicken is cooked through and the sweet potatoes are fork-tender and slightly browned.