Preheat the oven to 400°F (200°C).
Cook the brown rice according to package directions.
Cut the chicken into bite-sized pieces.
Toss the chicken with olive oil, garlic powder, onion powder, paprika, oregano, salt, pepper, and lemon juice.
Spread the chicken onto a baking sheet.
Place the broccoli, peppers, and carrots on another baking sheet.
Drizzle the vegetables with a little olive oil and season lightly.
Roast the chicken for 20–25 minutes until fully cooked.
Roast the vegetables for 18–20 minutes until tender.
Divide the cooked rice evenly among five meal prep containers.
Add equal portions of chicken to each container.
Top with the roasted vegetables.
Garnish with fresh parsley if desired.
Cool completely before sealing the containers.
Refrigerate for up to 4 days and reheat before serving.